New, unified interpretor/executor for vertex and fragment programs.

This replaces the code formerly in nvvertexec.c and s_fragprog.c.
Currently, DDX, DDY don't work.

1 files changed, 1585 insertions, 0 deletions

diff --git a/src/mesa/shader/prog_execute.c b/src/mesa/shader/prog_execute.c
new file mode 100644
index 00000000000..f466cc7affb
--- /dev/null
+++ b/src/mesa/shader/prog_execute.c
@@ -0,0 +1,1585 @@
+/*
+ * Mesa 3-D graphics library
+ * Version:  6.5.3
+ *
+ * Copyright (C) 1999-2007  Brian Paul   All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file prog_execute.c
+ * Software interpreter for vertex/fragment programs.
+ * \author Brian Paul
+ */
+
+/*
+ * NOTE: we do everything in single-precision floating point; we don't
+ * currently observe the single/half/fixed-precision qualifiers.
+ *
+ */
+
+
+#include "glheader.h"
+#include "colormac.h"
+#include "context.h"
+#include "program.h"
+#include "prog_execute.h"
+#include "prog_instruction.h"
+#include "prog_parameter.h"
+#include "prog_print.h"
+#include "slang_library_noise.h"
+
+
+/* See comments below for info about this */
+#define LAMBDA_ZERO 1
+
+/* debug predicate */
+#define DEBUG_PROG 0
+
+
+#if FEATURE_MESA_program_debug
+static struct gl_program_machine *CurrentMachine = NULL;
+
+/**
+ * For GL_MESA_program_debug.
+ * Return current value (4*GLfloat) of a program register.
+ * Called via ctx->Driver.GetFragmentProgramRegister().
+ */
+void
+_mesa_get_program_register(GLcontext *ctx, enum register_file file,
+                           GLuint index, GLfloat val[4])
+{
+   if (CurrentMachine) {
+      switch (file) {
+      case PROGRAM_INPUT:
+         if (CurrentMachine->CurProgram->Target == GL_VERTEX_PROGRAM_ARB) {
+            COPY_4V(val, CurrentMachine->VertAttribs[index]);
+         }
+         else {
+            COPY_4V(val,
+                    CurrentMachine->Attribs[index][CurrentMachine->CurElement]);
+         }
+         break;
+      case PROGRAM_OUTPUT:
+         COPY_4V(val, CurrentMachine->Outputs[index]);
+         break;
+      case PROGRAM_TEMPORARY:
+         COPY_4V(val, CurrentMachine->Temporaries[index]);
+         break;
+      default:
+         _mesa_problem(NULL,
+                       "bad register file in _swrast_get_program_register");
+      }
+   }
+}
+#endif /* FEATURE_MESA_program_debug */
+
+
+
+/**
+ * Return a pointer to the 4-element float vector specified by the given
+ * source register.
+ */
+static INLINE const GLfloat *
+get_register_pointer( GLcontext *ctx,
+                      const struct prog_src_register *source,
+                      const struct gl_program_machine *machine)
+{
+   /* XXX relative addressing... */
+   switch (source->File) {
+   case PROGRAM_TEMPORARY:
+      ASSERT(source->Index < MAX_PROGRAM_TEMPS);
+      return machine->Temporaries[source->Index];
+
+   case PROGRAM_INPUT:
+      if (machine->CurProgram->Target == GL_VERTEX_PROGRAM_ARB) {
+         ASSERT(source->Index < VERT_ATTRIB_MAX);
+         return machine->VertAttribs[source->Index];
+      }
+      else {
+         ASSERT(source->Index < FRAG_ATTRIB_MAX);
+         return machine->Attribs[source->Index][machine->CurElement];
+      }
+
+   case PROGRAM_OUTPUT:
+      /* This is only for PRINT */
+      ASSERT(source->Index < FRAG_RESULT_MAX);
+      return machine->Outputs[source->Index];
+
+   case PROGRAM_LOCAL_PARAM:
+      ASSERT(source->Index < MAX_PROGRAM_LOCAL_PARAMS);
+      return machine->CurProgram->LocalParams[source->Index];
+
+   case PROGRAM_ENV_PARAM:
+      ASSERT(source->Index < MAX_PROGRAM_ENV_PARAMS);
+      if (machine->CurProgram->Target == GL_VERTEX_PROGRAM_ARB)
+         return ctx->VertexProgram.Parameters[source->Index];
+      else
+         return ctx->FragmentProgram.Parameters[source->Index];
+
+   case PROGRAM_STATE_VAR:
+      /* Fallthrough */
+   case PROGRAM_CONSTANT:
+      /* Fallthrough */
+   case PROGRAM_UNIFORM:
+      /* Fallthrough */
+   case PROGRAM_NAMED_PARAM:
+      ASSERT(source->Index <
+             (GLint) machine->CurProgram->Parameters->NumParameters);
+      return machine->CurProgram->Parameters->ParameterValues[source->Index];
+
+   default:
+      _mesa_problem(ctx,
+                    "Invalid input register file %d in get_register_pointer()",
+                    source->File);
+      return NULL;
+   }
+}
+
+
+/**
+ * Fetch a 4-element float vector from the given source register.
+ * Apply swizzling and negating as needed.
+ */
+static void
+fetch_vector4( GLcontext *ctx,
+               const struct prog_src_register *source,
+               const struct gl_program_machine *machine,
+               const struct gl_program *program,
+               GLfloat result[4] )
+{
+   const GLfloat *src = get_register_pointer(ctx, source, machine);
+   ASSERT(src);
+
+   if (source->Swizzle == SWIZZLE_NOOP) {
+      /* no swizzling */
+      COPY_4V(result, src);
+   }
+   else {
+      ASSERT(GET_SWZ(source->Swizzle, 0) <= 3);
+      ASSERT(GET_SWZ(source->Swizzle, 1) <= 3);
+      ASSERT(GET_SWZ(source->Swizzle, 2) <= 3);
+      ASSERT(GET_SWZ(source->Swizzle, 3) <= 3);
+      result[0] = src[GET_SWZ(source->Swizzle, 0)];
+      result[1] = src[GET_SWZ(source->Swizzle, 1)];
+      result[2] = src[GET_SWZ(source->Swizzle, 2)];
+      result[3] = src[GET_SWZ(source->Swizzle, 3)];
+   }
+
+   if (source->NegateBase) {
+      result[0] = -result[0];
+      result[1] = -result[1];
+      result[2] = -result[2];
+      result[3] = -result[3];
+   }
+   if (source->Abs) {
+      result[0] = FABSF(result[0]);
+      result[1] = FABSF(result[1]);
+      result[2] = FABSF(result[2]);
+      result[3] = FABSF(result[3]);
+   }
+   if (source->NegateAbs) {
+      result[0] = -result[0];
+      result[1] = -result[1];
+      result[2] = -result[2];
+      result[3] = -result[3];
+   }
+}
+
+#if 0
+/**
+ * Fetch the derivative with respect to X for the given register.
+ * \return GL_TRUE if it was easily computed or GL_FALSE if we
+ * need to execute another instance of the program (ugh)!
+ */
+static GLboolean
+fetch_vector4_deriv( GLcontext *ctx,
+                     const struct prog_src_register *source,
+                     const SWspan *span,
+                     char xOrY, GLint column, GLfloat result[4] )
+{
+   GLfloat src[4];
+
+   ASSERT(xOrY == 'X' || xOrY == 'Y');
+
+   switch (source->Index) {
+   case FRAG_ATTRIB_WPOS:
+      if (xOrY == 'X') {
+         src[0] = 1.0;
+         src[1] = 0.0;
+         src[2] = span->attrStepX[FRAG_ATTRIB_WPOS][2]
+                / ctx->DrawBuffer->_DepthMaxF;
+         src[3] = span->attrStepX[FRAG_ATTRIB_WPOS][3];
+      }
+      else {
+         src[0] = 0.0;
+         src[1] = 1.0;
+         src[2] = span->attrStepY[FRAG_ATTRIB_WPOS][2]
+                / ctx->DrawBuffer->_DepthMaxF;
+         src[3] = span->attrStepY[FRAG_ATTRIB_WPOS][3];
+      }
+      break;
+   case FRAG_ATTRIB_COL0:
+   case FRAG_ATTRIB_COL1:
+      if (xOrY == 'X') {
+         src[0] = span->attrStepX[source->Index][0] * (1.0F / CHAN_MAXF);
+         src[1] = span->attrStepX[source->Index][1] * (1.0F / CHAN_MAXF);
+         src[2] = span->attrStepX[source->Index][2] * (1.0F / CHAN_MAXF);
+         src[3] = span->attrStepX[source->Index][3] * (1.0F / CHAN_MAXF);
+      }
+      else {
+         src[0] = span->attrStepY[source->Index][0] * (1.0F / CHAN_MAXF);
+         src[1] = span->attrStepY[source->Index][1] * (1.0F / CHAN_MAXF);
+         src[2] = span->attrStepY[source->Index][2] * (1.0F / CHAN_MAXF);
+         src[3] = span->attrStepY[source->Index][3] * (1.0F / CHAN_MAXF);
+      }
+      break;
+   case FRAG_ATTRIB_FOGC:
+      if (xOrY == 'X') {
+         src[0] = span->attrStepX[FRAG_ATTRIB_FOGC][0] * (1.0F / CHAN_MAXF);
+         src[1] = 0.0;
+         src[2] = 0.0;
+         src[3] = 0.0;
+      }
+      else {
+         src[0] = span->attrStepY[FRAG_ATTRIB_FOGC][0] * (1.0F / CHAN_MAXF);
+         src[1] = 0.0;
+         src[2] = 0.0;
+         src[3] = 0.0;
+      }
+      break;
+   default:
+      assert(source->Index < FRAG_ATTRIB_MAX);
+      /* texcoord or varying */
+      if (xOrY == 'X') {
+         /* this is a little tricky - I think I've got it right */
+         const GLfloat invQ = 1.0f / (span->attrStart[source->Index][3]
+                               + span->attrStepX[source->Index][3] * column);
+         src[0] = span->attrStepX[source->Index][0] * invQ;
+         src[1] = span->attrStepX[source->Index][1] * invQ;
+         src[2] = span->attrStepX[source->Index][2] * invQ;
+         src[3] = span->attrStepX[source->Index][3] * invQ;
+      }
+      else {
+         /* Tricky, as above, but in Y direction */
+         const GLfloat invQ = 1.0f / (span->attrStart[source->Index][3]
+                                      + span->attrStepY[source->Index][3]);
+         src[0] = span->attrStepY[source->Index][0] * invQ;
+         src[1] = span->attrStepY[source->Index][1] * invQ;
+         src[2] = span->attrStepY[source->Index][2] * invQ;
+         src[3] = span->attrStepY[source->Index][3] * invQ;
+      }
+      break;
+   }
+
+   result[0] = src[GET_SWZ(source->Swizzle, 0)];
+   result[1] = src[GET_SWZ(source->Swizzle, 1)];
+   result[2] = src[GET_SWZ(source->Swizzle, 2)];
+   result[3] = src[GET_SWZ(source->Swizzle, 3)];
+
+   if (source->NegateBase) {
+      result[0] = -result[0];
+      result[1] = -result[1];
+      result[2] = -result[2];
+      result[3] = -result[3];
+   }
+   if (source->Abs) {
+      result[0] = FABSF(result[0]);
+      result[1] = FABSF(result[1]);
+      result[2] = FABSF(result[2]);
+      result[3] = FABSF(result[3]);
+   }
+   if (source->NegateAbs) {
+      result[0] = -result[0];
+      result[1] = -result[1];
+      result[2] = -result[2];
+      result[3] = -result[3];
+   }
+   return GL_TRUE;
+}
+#endif
+
+
+/**
+ * As above, but only return result[0] element.
+ */
+static void
+fetch_vector1( GLcontext *ctx,
+               const struct prog_src_register *source,
+               const struct gl_program_machine *machine,
+               const struct gl_program *program,
+               GLfloat result[4] )
+{
+   const GLfloat *src = get_register_pointer(ctx, source, machine);
+   ASSERT(src);
+
+   result[0] = src[GET_SWZ(source->Swizzle, 0)];
+
+   if (source->NegateBase) {
+      result[0] = -result[0];
+   }
+   if (source->Abs) {
+      result[0] = FABSF(result[0]);
+   }
+   if (source->NegateAbs) {
+      result[0] = -result[0];
+   }
+}
+
+
+/**
+ * Test value against zero and return GT, LT, EQ or UN if NaN.
+ */
+static INLINE GLuint
+generate_cc( float value )
+{
+   if (value != value)
+      return COND_UN;  /* NaN */
+   if (value > 0.0F)
+      return COND_GT;
+   if (value < 0.0F)
+      return COND_LT;
+   return COND_EQ;
+}
+
+
+/**
+ * Test if the ccMaskRule is satisfied by the given condition code.
+ * Used to mask destination writes according to the current condition code.
+ */
+static INLINE GLboolean
+test_cc(GLuint condCode, GLuint ccMaskRule)
+{
+   switch (ccMaskRule) {
+   case COND_EQ: return (condCode == COND_EQ);
+   case COND_NE: return (condCode != COND_EQ);
+   case COND_LT: return (condCode == COND_LT);
+   case COND_GE: return (condCode == COND_GT || condCode == COND_EQ);
+   case COND_LE: return (condCode == COND_LT || condCode == COND_EQ);
+   case COND_GT: return (condCode == COND_GT);
+   case COND_TR: return GL_TRUE;
+   case COND_FL: return GL_FALSE;
+   default:      return GL_TRUE;
+   }
+}
+
+
+/**
+ * Evaluate the 4 condition codes against a predicate and return GL_TRUE
+ * or GL_FALSE to indicate result.
+ */
+static INLINE GLboolean
+eval_condition(const struct gl_program_machine *machine,
+               const struct prog_instruction *inst)
+{
+   const GLuint swizzle = inst->DstReg.CondSwizzle;
+   const GLuint condMask = inst->DstReg.CondMask;
+   if (test_cc(machine->CondCodes[GET_SWZ(swizzle, 0)], condMask) ||
+       test_cc(machine->CondCodes[GET_SWZ(swizzle, 1)], condMask) ||
+       test_cc(machine->CondCodes[GET_SWZ(swizzle, 2)], condMask) ||
+       test_cc(machine->CondCodes[GET_SWZ(swizzle, 3)], condMask)) {
+      return GL_TRUE;
+   }
+   else {
+      return GL_FALSE;
+   }
+}
+
+
+
+/**
+ * Store 4 floats into a register.  Observe the instructions saturate and
+ * set-condition-code flags.
+ */
+static void
+store_vector4( const struct prog_instruction *inst,
+               struct gl_program_machine *machine,
+               const GLfloat value[4] )
+{
+   const struct prog_dst_register *dest = &(inst->DstReg);
+   const GLboolean clamp = inst->SaturateMode == SATURATE_ZERO_ONE;
+   GLfloat *dstReg;
+   GLfloat dummyReg[4];
+   GLfloat clampedValue[4];
+   GLuint writeMask = dest->WriteMask;
+
+   switch (dest->File) {
+      case PROGRAM_OUTPUT:
+         dstReg = machine->Outputs[dest->Index];
+         break;
+      case PROGRAM_TEMPORARY:
+         dstReg = machine->Temporaries[dest->Index];
+         break;
+      case PROGRAM_WRITE_ONLY:
+         dstReg = dummyReg;
+         return;
+      default:
+         _mesa_problem(NULL, "bad register file in store_vector4(fp)");
+         return;
+   }
+
+#if 0
+   if (value[0] > 1.0e10 ||
+       IS_INF_OR_NAN(value[0]) ||
+       IS_INF_OR_NAN(value[1]) ||
+       IS_INF_OR_NAN(value[2]) ||
+       IS_INF_OR_NAN(value[3])  )
+      printf("store %g %g %g %g\n", value[0], value[1], value[2], value[3]);
+#endif
+
+   if (clamp) {
+      clampedValue[0] = CLAMP(value[0], 0.0F, 1.0F);
+      clampedValue[1] = CLAMP(value[1], 0.0F, 1.0F);
+      clampedValue[2] = CLAMP(value[2], 0.0F, 1.0F);
+      clampedValue[3] = CLAMP(value[3], 0.0F, 1.0F);
+      value = clampedValue;
+   }
+
+   if (dest->CondMask != COND_TR) {
+      /* condition codes may turn off some writes */
+      if (writeMask & WRITEMASK_X) {
+         if (!test_cc(machine->CondCodes[GET_SWZ(dest->CondSwizzle, 0)],
+                      dest->CondMask))
+            writeMask &= ~WRITEMASK_X;
+      }
+      if (writeMask & WRITEMASK_Y) {
+         if (!test_cc(machine->CondCodes[GET_SWZ(dest->CondSwizzle, 1)],
+                      dest->CondMask))
+            writeMask &= ~WRITEMASK_Y;
+      }
+      if (writeMask & WRITEMASK_Z) {
+         if (!test_cc(machine->CondCodes[GET_SWZ(dest->CondSwizzle, 2)],
+                      dest->CondMask))
+            writeMask &= ~WRITEMASK_Z;
+      }
+      if (writeMask & WRITEMASK_W) {
+         if (!test_cc(machine->CondCodes[GET_SWZ(dest->CondSwizzle, 3)],
+                      dest->CondMask))
+            writeMask &= ~WRITEMASK_W;
+      }
+   }
+
+   if (writeMask & WRITEMASK_X)
+      dstReg[0] = value[0];
+   if (writeMask & WRITEMASK_Y)
+      dstReg[1] = value[1];
+   if (writeMask & WRITEMASK_Z)
+      dstReg[2] = value[2];
+   if (writeMask & WRITEMASK_W)
+      dstReg[3] = value[3];
+
+   if (inst->CondUpdate) {
+      if (writeMask & WRITEMASK_X)
+         machine->CondCodes[0] = generate_cc(value[0]);
+      if (writeMask & WRITEMASK_Y)
+         machine->CondCodes[1] = generate_cc(value[1]);
+      if (writeMask & WRITEMASK_Z)
+         machine->CondCodes[2] = generate_cc(value[2]);
+      if (writeMask & WRITEMASK_W)
+         machine->CondCodes[3] = generate_cc(value[3]);
+   }
+}
+
+
+#if 0
+/**
+ * Initialize a new machine state instance from an existing one, adding
+ * the partial derivatives onto the input registers.
+ * Used to implement DDX and DDY instructions in non-trivial cases.
+ */
+static void
+init_machine_deriv( GLcontext *ctx,
+                    const struct gl_program_machine *machine,
+                    const struct gl_fragment_program *program,
+                    const SWspan *span, char xOrY,
+                    struct gl_program_machine *dMachine )
+{
+   GLuint attr;
+
+   ASSERT(xOrY == 'X' || xOrY == 'Y');
+
+   /* copy existing machine */
+   _mesa_memcpy(dMachine, machine, sizeof(struct gl_program_machine));
+
+   if (program->Base.Target == GL_FRAGMENT_PROGRAM_NV) {
+      /* XXX also need to do this when using valgrind */
+      /* Clear temporary registers (undefined for ARB_f_p) */
+      _mesa_bzero( (void*) machine->Temporaries,
+                   MAX_PROGRAM_TEMPS * 4 * sizeof(GLfloat));
+   }
+
+   /* Add derivatives */
+   if (program->Base.InputsRead & FRAG_BIT_WPOS) {
+      GLfloat *wpos = machine->Attribs[FRAG_ATTRIB_WPOS][machine->CurElement];
+      if (xOrY == 'X') {
+         wpos[0] += 1.0F;
+         wpos[1] += 0.0F;
+         wpos[2] += span->attrStepX[FRAG_ATTRIB_WPOS][2];
+         wpos[3] += span->attrStepX[FRAG_ATTRIB_WPOS][3];
+      }
+      else {
+         wpos[0] += 0.0F;
+         wpos[1] += 1.0F;
+         wpos[2] += span->attrStepY[FRAG_ATTRIB_WPOS][2];
+         wpos[3] += span->attrStepY[FRAG_ATTRIB_WPOS][3];
+      }
+   }
+
+   /* primary, secondary colors */
+   for (attr = FRAG_ATTRIB_COL0; attr <= FRAG_ATTRIB_COL1; attr++) {
+      if (program->Base.InputsRead & (1 << attr)) {
+         GLfloat *col = machine->Attribs[attr][machine->CurElement];
+         if (xOrY == 'X') {
+            col[0] += span->attrStepX[attr][0] * (1.0F / CHAN_MAXF);
+            col[1] += span->attrStepX[attr][1] * (1.0F / CHAN_MAXF);
+            col[2] += span->attrStepX[attr][2] * (1.0F / CHAN_MAXF);
+            col[3] += span->attrStepX[attr][3] * (1.0F / CHAN_MAXF);
+         }
+         else {
+            col[0] += span->attrStepY[attr][0] * (1.0F / CHAN_MAXF);
+            col[1] += span->attrStepY[attr][1] * (1.0F / CHAN_MAXF);
+            col[2] += span->attrStepY[attr][2] * (1.0F / CHAN_MAXF);
+            col[3] += span->attrStepY[attr][3] * (1.0F / CHAN_MAXF);
+         }
+      }
+   }
+   if (program->Base.InputsRead & FRAG_BIT_FOGC) {
+      GLfloat *fogc = machine->Attribs[FRAG_ATTRIB_FOGC][machine->CurElement];
+      if (xOrY == 'X') {
+         fogc[0] += span->attrStepX[FRAG_ATTRIB_FOGC][0];
+      }
+      else {
+         fogc[0] += span->attrStepY[FRAG_ATTRIB_FOGC][0];
+      }
+   }
+   /* texcoord and varying vars */
+   for (attr = FRAG_ATTRIB_TEX0; attr < FRAG_ATTRIB_MAX; attr++) {
+      if (program->Base.InputsRead & (1 << attr)) {
+         GLfloat *val = machine->Attribs[attr][machine->CurElement];
+         /* XXX perspective-correct interpolation */
+         if (xOrY == 'X') {
+            val[0] += span->attrStepX[attr][0];
+            val[1] += span->attrStepX[attr][1];
+            val[2] += span->attrStepX[attr][2];
+            val[3] += span->attrStepX[attr][3];
+         }
+         else {
+            val[0] += span->attrStepY[attr][0];
+            val[1] += span->attrStepY[attr][1];
+            val[2] += span->attrStepY[attr][2];
+            val[3] += span->attrStepY[attr][3];
+         }
+      }
+   }
+
+   /* init condition codes */
+   dMachine->CondCodes[0] = COND_EQ;
+   dMachine->CondCodes[1] = COND_EQ;
+   dMachine->CondCodes[2] = COND_EQ;
+   dMachine->CondCodes[3] = COND_EQ;
+}
+#endif
+
+
+/**
+ * Execute the given vertex/fragment program.
+ *
+ * \param ctx - rendering context
+ * \param program - the fragment program to execute
+ * \param machine - machine state (register file)
+ * \param maxInst - max number of instructions to execute
+ * \return GL_TRUE if program completed or GL_FALSE if program executed KIL.
+ */
+GLboolean
+_mesa_execute_program(GLcontext *ctx,
+                      const struct gl_program *program, GLuint maxInst,
+                      struct gl_program_machine *machine, GLuint element)
+{
+   const GLuint MAX_EXEC = 10000;
+   GLint pc, total = 0;
+
+   machine->CurProgram = program;
+
+   if (DEBUG_PROG) {
+      printf("execute program %u --------------------\n", program->Id);
+   }
+
+#if FEATURE_MESA_program_debug
+   CurrentMachine = machine;
+#endif
+
+   for (pc = 0; pc < maxInst; pc++) {
+      const struct prog_instruction *inst = program->Instructions + pc;
+
+#if FEATURE_MESA_program_debug
+      if (ctx->FragmentProgram.CallbackEnabled &&
+          ctx->FragmentProgram.Callback) {
+         ctx->FragmentProgram.CurrentPosition = inst->StringPos;
+         ctx->FragmentProgram.Callback(program->Target,
+                                       ctx->FragmentProgram.CallbackData);
+      }
+#endif
+
+      if (DEBUG_PROG) {
+         _mesa_print_instruction(inst);
+      }
+
+      switch (inst->Opcode) {
+         case OPCODE_ABS:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = FABSF(a[0]);
+               result[1] = FABSF(a[1]);
+               result[2] = FABSF(a[2]);
+               result[3] = FABSF(a[3]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_ADD:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = a[0] + b[0];
+               result[1] = a[1] + b[1];
+               result[2] = a[2] + b[2];
+               result[3] = a[3] + b[3];
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("ADD (%g %g %g %g) = (%g %g %g %g) + (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3], 
+                         a[0], a[1], a[2], a[3],
+                         b[0], b[1], b[2], b[3]);
+               }
+            }
+            break;
+         case OPCODE_BGNLOOP:
+            /* no-op */
+            break;
+         case OPCODE_ENDLOOP:
+            /* subtract 1 here since pc is incremented by for(pc) loop */
+            pc = inst->BranchTarget - 1; /* go to matching BNGLOOP */
+            break;
+         case OPCODE_BGNSUB: /* begin subroutine */
+            break;
+         case OPCODE_ENDSUB: /* end subroutine */
+            break;
+         case OPCODE_BRA: /* branch (conditional) */
+            /* fall-through */
+         case OPCODE_BRK: /* break out of loop (conditional) */
+            /* fall-through */
+         case OPCODE_CONT: /* continue loop (conditional) */
+            if (eval_condition(machine, inst)) {
+               /* take branch */
+               /* Subtract 1 here since we'll do pc++ at end of for-loop */
+               pc = inst->BranchTarget - 1;
+            }
+            break;
+         case OPCODE_CAL: /* Call subroutine (conditional) */
+            if (eval_condition(machine, inst)) {
+               /* call the subroutine */
+               if (machine->StackDepth >= MAX_PROGRAM_CALL_DEPTH) {
+                  return GL_TRUE; /* Per GL_NV_vertex_program2 spec */
+               }
+               machine->CallStack[machine->StackDepth++] = pc + 1;
+               pc = inst->BranchTarget; /* XXX - 1 ??? */
+            }
+            break;
+         case OPCODE_CMP:
+            {
+               GLfloat a[4], b[4], c[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               fetch_vector4( ctx, &inst->SrcReg[2], machine, program, c );
+               result[0] = a[0] < 0.0F ? b[0] : c[0];
+               result[1] = a[1] < 0.0F ? b[1] : c[1];
+               result[2] = a[2] < 0.0F ? b[2] : c[2];
+               result[3] = a[3] < 0.0F ? b[3] : c[3];
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_COS:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = result[1] = result[2] = result[3]
+                  = (GLfloat) _mesa_cos(a[0]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_DDX: /* Partial derivative with respect to X */
+            {
+#if 0
+               GLfloat a[4], aNext[4], result[4];
+               struct gl_program_machine dMachine;
+               if (!fetch_vector4_deriv(ctx, &inst->SrcReg[0], span, 'X',
+                                        column, result)) {
+                  /* This is tricky.  Make a copy of the current machine state,
+                   * increment the input registers by the dx or dy partial
+                   * derivatives, then re-execute the program up to the
+                   * preceeding instruction, then fetch the source register.
+                   * Finally, find the difference in the register values for
+                   * the original and derivative runs.
+                   */
+                  fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a);
+                  init_machine_deriv(ctx, machine, program, span,
+                                     'X', &dMachine);
+                  execute_program(ctx, program, pc, &dMachine, span, column);
+                  fetch_vector4( ctx, &inst->SrcReg[0], &dMachine, program, aNext );
+                  result[0] = aNext[0] - a[0];
+                  result[1] = aNext[1] - a[1];
+                  result[2] = aNext[2] - a[2];
+                  result[3] = aNext[3] - a[3];
+               }
+               store_vector4( inst, machine, result );
+#else
+               static const GLfloat result[4] = { 0, 0, 0, 0 };
+               store_vector4( inst, machine, result );
+#endif
+            }
+            break;
+         case OPCODE_DDY: /* Partial derivative with respect to Y */
+            {
+#if 0
+               GLfloat a[4], aNext[4], result[4];
+               struct gl_program_machine dMachine;
+               if (!fetch_vector4_deriv(ctx, &inst->SrcReg[0], span, 'Y',
+                                        column, result)) {
+                  init_machine_deriv(ctx, machine, program, span,
+                                     'Y', &dMachine);
+                  fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a);
+                  execute_program(ctx, program, pc, &dMachine, span, column);
+                  fetch_vector4( ctx, &inst->SrcReg[0], &dMachine, program, aNext );
+                  result[0] = aNext[0] - a[0];
+                  result[1] = aNext[1] - a[1];
+                  result[2] = aNext[2] - a[2];
+                  result[3] = aNext[3] - a[3];
+               }
+               store_vector4( inst, machine, result );
+#else
+               static const GLfloat result[4] = { 0, 0, 0, 0 };
+               store_vector4( inst, machine, result );
+#endif
+            }
+            break;
+         case OPCODE_DP3:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = result[1] = result[2] = result[3] = DOT3(a, b);
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("DP3 %g = (%g %g %g) . (%g %g %g)\n",
+                         result[0], a[0], a[1], a[2], b[0], b[1], b[2]);
+               }
+            }
+            break;
+         case OPCODE_DP4:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = result[1] = result[2] = result[3] = DOT4(a,b);
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("DP4 %g = (%g, %g %g %g) . (%g, %g %g %g)\n",
+                         result[0], a[0], a[1], a[2], a[3],
+                         b[0], b[1], b[2], b[3]);
+               }
+            }
+            break;
+         case OPCODE_DPH:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = result[1] = result[2] = result[3] = 
+                  a[0] * b[0] + a[1] * b[1] + a[2] * b[2] + b[3];
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_DST: /* Distance vector */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = 1.0F;
+               result[1] = a[1] * b[1];
+               result[2] = a[2];
+               result[3] = b[3];
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_EX2: /* Exponential base 2 */
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = result[1] = result[2] = result[3] =
+                  (GLfloat) _mesa_pow(2.0, a[0]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_FLR:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = FLOORF(a[0]);
+               result[1] = FLOORF(a[1]);
+               result[2] = FLOORF(a[2]);
+               result[3] = FLOORF(a[3]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_FRC:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = a[0] - FLOORF(a[0]);
+               result[1] = a[1] - FLOORF(a[1]);
+               result[2] = a[2] - FLOORF(a[2]);
+               result[3] = a[3] - FLOORF(a[3]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_IF:
+            if (eval_condition(machine, inst)) {
+               /* do if-clause (just continue execution) */
+            }
+            else {
+               /* go to the instruction after ELSE or ENDIF */
+               assert(inst->BranchTarget >= 0);
+               pc = inst->BranchTarget - 1;
+            }
+            break;
+         case OPCODE_ELSE:
+            /* goto ENDIF */
+            assert(inst->BranchTarget >= 0);
+            pc = inst->BranchTarget - 1;
+            break;
+         case OPCODE_ENDIF:
+            /* nothing */
+            break;
+         case OPCODE_INT: /* float to int */
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = (GLfloat) (GLint) a[0];
+               result[1] = (GLfloat) (GLint) a[1];
+               result[2] = (GLfloat) (GLint) a[2];
+               result[3] = (GLfloat) (GLint) a[3];
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_KIL_NV: /* NV_f_p only (conditional) */
+            if (eval_condition(machine, inst)) {
+               return GL_FALSE;
+            }
+            break;
+         case OPCODE_KIL: /* ARB_f_p only */
+            {
+               GLfloat a[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               if (a[0] < 0.0F || a[1] < 0.0F || a[2] < 0.0F || a[3] < 0.0F) {
+                  return GL_FALSE;
+               }
+            }
+            break;
+         case OPCODE_LG2:  /* log base 2 */
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = result[1] = result[2] = result[3] = LOG2(a[0]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_LIT:
+            {
+               const GLfloat epsilon = 1.0F / 256.0F; /* from NV VP spec */
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               a[0] = MAX2(a[0], 0.0F);
+               a[1] = MAX2(a[1], 0.0F);
+               /* XXX ARB version clamps a[3], NV version doesn't */
+               a[3] = CLAMP(a[3], -(128.0F - epsilon), (128.0F - epsilon));
+               result[0] = 1.0F;
+               result[1] = a[0];
+               /* XXX we could probably just use pow() here */
+               if (a[0] > 0.0F) {
+                  if (a[1] == 0.0 && a[3] == 0.0)
+                     result[2] = 1.0;
+                  else
+                     result[2] = EXPF(a[3] * LOGF(a[1]));
+               }
+               else {
+                  result[2] = 0.0;
+               }
+               result[3] = 1.0F;
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("LIT (%g %g %g %g) : (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3],
+                         a[0], a[1], a[2], a[3]);
+               }
+            }
+            break;
+         case OPCODE_LRP:
+            {
+               GLfloat a[4], b[4], c[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               fetch_vector4( ctx, &inst->SrcReg[2], machine, program, c );
+               result[0] = a[0] * b[0] + (1.0F - a[0]) * c[0];
+               result[1] = a[1] * b[1] + (1.0F - a[1]) * c[1];
+               result[2] = a[2] * b[2] + (1.0F - a[2]) * c[2];
+               result[3] = a[3] * b[3] + (1.0F - a[3]) * c[3];
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("LRP (%g %g %g %g) = (%g %g %g %g), "
+                         "(%g %g %g %g), (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3],
+                         a[0], a[1], a[2], a[3],
+                         b[0], b[1], b[2], b[3],
+                         c[0], c[1], c[2], c[3]);
+               }
+            }
+            break;
+         case OPCODE_MAD:
+            {
+               GLfloat a[4], b[4], c[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               fetch_vector4( ctx, &inst->SrcReg[2], machine, program, c );
+               result[0] = a[0] * b[0] + c[0];
+               result[1] = a[1] * b[1] + c[1];
+               result[2] = a[2] * b[2] + c[2];
+               result[3] = a[3] * b[3] + c[3];
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("MAD (%g %g %g %g) = (%g %g %g %g) * "
+                         "(%g %g %g %g) + (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3],
+                         a[0], a[1], a[2], a[3],
+                         b[0], b[1], b[2], b[3],
+                         c[0], c[1], c[2], c[3]);
+               }
+            }
+            break;
+         case OPCODE_MAX:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = MAX2(a[0], b[0]);
+               result[1] = MAX2(a[1], b[1]);
+               result[2] = MAX2(a[2], b[2]);
+               result[3] = MAX2(a[3], b[3]);
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("MAX (%g %g %g %g) = (%g %g %g %g), (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3], 
+                         a[0], a[1], a[2], a[3],
+                         b[0], b[1], b[2], b[3]);
+               }
+            }
+            break;
+         case OPCODE_MIN:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = MIN2(a[0], b[0]);
+               result[1] = MIN2(a[1], b[1]);
+               result[2] = MIN2(a[2], b[2]);
+               result[3] = MIN2(a[3], b[3]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_MOV:
+            {
+               GLfloat result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, result );
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("MOV (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3]);
+               }
+            }
+            break;
+         case OPCODE_MUL:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = a[0] * b[0];
+               result[1] = a[1] * b[1];
+               result[2] = a[2] * b[2];
+               result[3] = a[3] * b[3];
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("MUL (%g %g %g %g) = (%g %g %g %g) * (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3], 
+                         a[0], a[1], a[2], a[3],
+                         b[0], b[1], b[2], b[3]);
+               }
+            }
+            break;
+         case OPCODE_NOISE1:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] =
+               result[1] =
+               result[2] =
+               result[3] = _slang_library_noise1(a[0]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_NOISE2:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] =
+               result[1] =
+               result[2] =
+               result[3] = _slang_library_noise2(a[0], a[1]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_NOISE3:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] =
+               result[1] =
+               result[2] =
+               result[3] = _slang_library_noise3(a[0], a[1], a[2]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_NOISE4:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] =
+               result[1] =
+               result[2] =
+               result[3] = _slang_library_noise4(a[0], a[1], a[2], a[3]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_NOP:
+            break;
+         case OPCODE_PK2H: /* pack two 16-bit floats in one 32-bit float */
+            {
+               GLfloat a[4], result[4];
+               GLhalfNV hx, hy;
+               GLuint *rawResult = (GLuint *) result;
+               GLuint twoHalves;
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               hx = _mesa_float_to_half(a[0]);
+               hy = _mesa_float_to_half(a[1]);
+               twoHalves = hx | (hy << 16);
+               rawResult[0] = rawResult[1] = rawResult[2] = rawResult[3]
+                  = twoHalves;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_PK2US: /* pack two GLushorts into one 32-bit float */
+            {
+               GLfloat a[4], result[4];
+               GLuint usx, usy, *rawResult = (GLuint *) result;
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               a[0] = CLAMP(a[0], 0.0F, 1.0F);
+               a[1] = CLAMP(a[1], 0.0F, 1.0F);
+               usx = IROUND(a[0] * 65535.0F);
+               usy = IROUND(a[1] * 65535.0F);
+               rawResult[0] = rawResult[1] = rawResult[2] = rawResult[3]
+                  = usx | (usy << 16);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_PK4B: /* pack four GLbytes into one 32-bit float */
+            {
+               GLfloat a[4], result[4];
+               GLuint ubx, uby, ubz, ubw, *rawResult = (GLuint *) result;
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               a[0] = CLAMP(a[0], -128.0F / 127.0F, 1.0F);
+               a[1] = CLAMP(a[1], -128.0F / 127.0F, 1.0F);
+               a[2] = CLAMP(a[2], -128.0F / 127.0F, 1.0F);
+               a[3] = CLAMP(a[3], -128.0F / 127.0F, 1.0F);
+               ubx = IROUND(127.0F * a[0] + 128.0F);
+               uby = IROUND(127.0F * a[1] + 128.0F);
+               ubz = IROUND(127.0F * a[2] + 128.0F);
+               ubw = IROUND(127.0F * a[3] + 128.0F);
+               rawResult[0] = rawResult[1] = rawResult[2] = rawResult[3]
+                  = ubx | (uby << 8) | (ubz << 16) | (ubw << 24);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_PK4UB: /* pack four GLubytes into one 32-bit float */
+            {
+               GLfloat a[4], result[4];
+               GLuint ubx, uby, ubz, ubw, *rawResult = (GLuint *) result;
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               a[0] = CLAMP(a[0], 0.0F, 1.0F);
+               a[1] = CLAMP(a[1], 0.0F, 1.0F);
+               a[2] = CLAMP(a[2], 0.0F, 1.0F);
+               a[3] = CLAMP(a[3], 0.0F, 1.0F);
+               ubx = IROUND(255.0F * a[0]);
+               uby = IROUND(255.0F * a[1]);
+               ubz = IROUND(255.0F * a[2]);
+               ubw = IROUND(255.0F * a[3]);
+               rawResult[0] = rawResult[1] = rawResult[2] = rawResult[3]
+                  = ubx | (uby << 8) | (ubz << 16) | (ubw << 24);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_POW:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector1( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = result[1] = result[2] = result[3]
+                  = (GLfloat)_mesa_pow(a[0], b[0]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_RCP:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               if (DEBUG_PROG) {
+                  if (a[0] == 0)
+                     printf("RCP(0)\n");
+                  else if (IS_INF_OR_NAN(a[0]))
+                     printf("RCP(inf)\n");
+               }
+               result[0] = result[1] = result[2] = result[3] = 1.0F / a[0];
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_RET: /* return from subroutine (conditional) */
+            if (eval_condition(machine, inst)) {
+               if (machine->StackDepth == 0) {
+                  return GL_TRUE; /* Per GL_NV_vertex_program2 spec */
+               }
+               pc = machine->CallStack[--machine->StackDepth];
+            }
+            break;
+         case OPCODE_RFL: /* reflection vector */
+            {
+               GLfloat axis[4], dir[4], result[4], tmpX, tmpW;
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, axis );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, dir );
+               tmpW = DOT3(axis, axis);
+               tmpX = (2.0F * DOT3(axis, dir)) / tmpW;
+               result[0] = tmpX * axis[0] - dir[0];
+               result[1] = tmpX * axis[1] - dir[1];
+               result[2] = tmpX * axis[2] - dir[2];
+               /* result[3] is never written! XXX enforce in parser! */
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_RSQ: /* 1 / sqrt() */
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               a[0] = FABSF(a[0]);
+               result[0] = result[1] = result[2] = result[3] = INV_SQRTF(a[0]);
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("RSQ %g = 1/sqrt(|%g|)\n", result[0], a[0]);
+               }
+            }
+            break;
+         case OPCODE_SCS: /* sine and cos */
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = (GLfloat) _mesa_cos(a[0]);
+               result[1] = (GLfloat) _mesa_sin(a[0]);
+               result[2] = 0.0;  /* undefined! */
+               result[3] = 0.0;  /* undefined! */
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SEQ: /* set on equal */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = (a[0] == b[0]) ? 1.0F : 0.0F;
+               result[1] = (a[1] == b[1]) ? 1.0F : 0.0F;
+               result[2] = (a[2] == b[2]) ? 1.0F : 0.0F;
+               result[3] = (a[3] == b[3]) ? 1.0F : 0.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SFL: /* set false, operands ignored */
+            {
+               static const GLfloat result[4] = { 0.0F, 0.0F, 0.0F, 0.0F };
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SGE: /* set on greater or equal */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = (a[0] >= b[0]) ? 1.0F : 0.0F;
+               result[1] = (a[1] >= b[1]) ? 1.0F : 0.0F;
+               result[2] = (a[2] >= b[2]) ? 1.0F : 0.0F;
+               result[3] = (a[3] >= b[3]) ? 1.0F : 0.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SGT: /* set on greater */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = (a[0] > b[0]) ? 1.0F : 0.0F;
+               result[1] = (a[1] > b[1]) ? 1.0F : 0.0F;
+               result[2] = (a[2] > b[2]) ? 1.0F : 0.0F;
+               result[3] = (a[3] > b[3]) ? 1.0F : 0.0F;
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("SGT %g %g %g %g\n",
+                         result[0], result[1], result[2], result[3]);
+               }
+            }
+            break;
+         case OPCODE_SIN:
+            {
+               GLfloat a[4], result[4];
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = result[1] = result[2] = result[3]
+                  = (GLfloat) _mesa_sin(a[0]);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SLE: /* set on less or equal */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = (a[0] <= b[0]) ? 1.0F : 0.0F;
+               result[1] = (a[1] <= b[1]) ? 1.0F : 0.0F;
+               result[2] = (a[2] <= b[2]) ? 1.0F : 0.0F;
+               result[3] = (a[3] <= b[3]) ? 1.0F : 0.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SLT: /* set on less */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = (a[0] < b[0]) ? 1.0F : 0.0F;
+               result[1] = (a[1] < b[1]) ? 1.0F : 0.0F;
+               result[2] = (a[2] < b[2]) ? 1.0F : 0.0F;
+               result[3] = (a[3] < b[3]) ? 1.0F : 0.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SNE: /* set on not equal */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = (a[0] != b[0]) ? 1.0F : 0.0F;
+               result[1] = (a[1] != b[1]) ? 1.0F : 0.0F;
+               result[2] = (a[2] != b[2]) ? 1.0F : 0.0F;
+               result[3] = (a[3] != b[3]) ? 1.0F : 0.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_STR: /* set true, operands ignored */
+            {
+               static const GLfloat result[4] = { 1.0F, 1.0F, 1.0F, 1.0F };
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_SUB:
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = a[0] - b[0];
+               result[1] = a[1] - b[1];
+               result[2] = a[2] - b[2];
+               result[3] = a[3] - b[3];
+               store_vector4( inst, machine, result );
+               if (DEBUG_PROG) {
+                  printf("SUB (%g %g %g %g) = (%g %g %g %g) - (%g %g %g %g)\n",
+                         result[0], result[1], result[2], result[3],
+                         a[0], a[1], a[2], a[3], b[0], b[1], b[2], b[3]);
+               }
+            }
+            break;
+         case OPCODE_SWZ: /* extended swizzle */
+            {
+               const struct prog_src_register *source = &inst->SrcReg[0];
+               const GLfloat *src = get_register_pointer(ctx, source, machine);
+               GLfloat result[4];
+               GLuint i;
+               for (i = 0; i < 4; i++) {
+                  const GLuint swz = GET_SWZ(source->Swizzle, i);
+                  if (swz == SWIZZLE_ZERO)
+                     result[i] = 0.0;
+                  else if (swz == SWIZZLE_ONE)
+                     result[i] = 1.0;
+                  else {
+                     ASSERT(swz >= 0);
+                     ASSERT(swz <= 3);
+                     result[i] = src[swz];
+                  }
+                  if (source->NegateBase & (1 << i))
+                     result[i] = -result[i];
+               }
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_TEX: /* Both ARB and NV frag prog */
+            /* Texel lookup */
+            {
+               /* Note: only use the precomputed lambda value when we're
+                * sampling texture unit [K] with texcoord[K].
+                * Otherwise, the lambda value may have no relation to the
+                * instruction's texcoord or texture image.  Using the wrong
+                * lambda is usually bad news.
+                * The rest of the time, just use zero (until we get a more
+                * sophisticated way of computing lambda).
+                */
+               GLfloat coord[4], color[4], lambda;
+#if 0
+               if (inst->SrcReg[0].File == PROGRAM_INPUT &&
+                   inst->SrcReg[0].Index == FRAG_ATTRIB_TEX0+inst->TexSrcUnit)
+                  lambda = span->array->lambda[inst->TexSrcUnit][column];
+               else
+#endif
+                  lambda = 0.0;
+               fetch_vector4(ctx, &inst->SrcReg[0], machine, program, coord);
+               machine->FetchTexelLod(ctx, coord, lambda, inst->TexSrcUnit, color);
+               if (DEBUG_PROG) {
+                  printf("TEX (%g, %g, %g, %g) = texture[%d][%g, %g, %g, %g], "
+                         "lod %f\n",
+                         color[0], color[1], color[2], color[3],
+                         inst->TexSrcUnit,
+                         coord[0], coord[1], coord[2], coord[3], lambda);
+               }
+               store_vector4( inst, machine, color );
+            }
+            break;
+         case OPCODE_TXB: /* GL_ARB_fragment_program only */
+            /* Texel lookup with LOD bias */
+            {
+               const struct gl_texture_unit *texUnit
+                  = &ctx->Texture.Unit[inst->TexSrcUnit];
+               GLfloat coord[4], color[4], lambda, bias;
+#if 0
+               if (inst->SrcReg[0].File == PROGRAM_INPUT &&
+                   inst->SrcReg[0].Index == FRAG_ATTRIB_TEX0+inst->TexSrcUnit)
+                  lambda = span->array->lambda[inst->TexSrcUnit][column];
+               else
+#endif
+                  lambda = 0.0;
+               fetch_vector4(ctx, &inst->SrcReg[0], machine, program, coord);
+               /* coord[3] is the bias to add to lambda */
+               bias = texUnit->LodBias + coord[3];
+               if (texUnit->_Current)
+                  bias += texUnit->_Current->LodBias;
+               machine->FetchTexelLod(ctx, coord, lambda + bias,
+                                      inst->TexSrcUnit, color);
+               store_vector4( inst, machine, color );
+            }
+            break;
+         case OPCODE_TXD: /* GL_NV_fragment_program only */
+            /* Texture lookup w/ partial derivatives for LOD */
+            {
+               GLfloat texcoord[4], dtdx[4], dtdy[4], color[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, texcoord );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, dtdx );
+               fetch_vector4( ctx, &inst->SrcReg[2], machine, program, dtdy );
+               machine->FetchTexelDeriv(ctx, texcoord, dtdx, dtdy,
+                                        inst->TexSrcUnit, color );
+               store_vector4( inst, machine, color );
+            }
+            break;
+         case OPCODE_TXP: /* GL_ARB_fragment_program only */
+            /* Texture lookup w/ projective divide */
+            {
+               GLfloat texcoord[4], color[4], lambda;
+#if 0
+               if (inst->SrcReg[0].File == PROGRAM_INPUT &&
+                   inst->SrcReg[0].Index == FRAG_ATTRIB_TEX0+inst->TexSrcUnit)
+                  lambda = span->array->lambda[inst->TexSrcUnit][column];
+               else
+#endif
+                  lambda = 0.0;
+               fetch_vector4(ctx, &inst->SrcReg[0], machine, program,texcoord);
+	       /* Not so sure about this test - if texcoord[3] is
+		* zero, we'd probably be fine except for an ASSERT in
+		* IROUND_POS() which gets triggered by the inf values created.
+		*/
+	       if (texcoord[3] != 0.0) {
+		  texcoord[0] /= texcoord[3];
+		  texcoord[1] /= texcoord[3];
+		  texcoord[2] /= texcoord[3];
+	       }
+               machine->FetchTexelLod(ctx, texcoord, lambda,
+                                      inst->TexSrcUnit, color);
+               store_vector4( inst, machine, color );
+            }
+            break;
+         case OPCODE_TXP_NV: /* GL_NV_fragment_program only */
+            /* Texture lookup w/ projective divide */
+            {
+               GLfloat texcoord[4], color[4], lambda;
+#if 0
+               if (inst->SrcReg[0].File == PROGRAM_INPUT &&
+                   inst->SrcReg[0].Index == FRAG_ATTRIB_TEX0+inst->TexSrcUnit)
+                  lambda = span->array->lambda[inst->TexSrcUnit][column];
+               else
+#endif
+                  lambda = 0.0;
+               fetch_vector4(ctx, &inst->SrcReg[0], machine, program,texcoord);
+               if (inst->TexSrcTarget != TEXTURE_CUBE_INDEX &&
+		   texcoord[3] != 0.0) {
+                  texcoord[0] /= texcoord[3];
+                  texcoord[1] /= texcoord[3];
+                  texcoord[2] /= texcoord[3];
+               }
+               machine->FetchTexelLod(ctx, texcoord, lambda,
+                                      inst->TexSrcUnit, color);
+               store_vector4( inst, machine, color );
+            }
+            break;
+         case OPCODE_UP2H: /* unpack two 16-bit floats */
+            {
+               GLfloat a[4], result[4];
+               const GLuint *rawBits = (const GLuint *) a;
+               GLhalfNV hx, hy;
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               hx = rawBits[0] & 0xffff;
+               hy = rawBits[0] >> 16;
+               result[0] = result[2] = _mesa_half_to_float(hx);
+               result[1] = result[3] = _mesa_half_to_float(hy);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_UP2US: /* unpack two GLushorts */
+            {
+               GLfloat a[4], result[4];
+               const GLuint *rawBits = (const GLuint *) a;
+               GLushort usx, usy;
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               usx = rawBits[0] & 0xffff;
+               usy = rawBits[0] >> 16;
+               result[0] = result[2] = usx * (1.0f / 65535.0f);
+               result[1] = result[3] = usy * (1.0f / 65535.0f);
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_UP4B: /* unpack four GLbytes */
+            {
+               GLfloat a[4], result[4];
+               const GLuint *rawBits = (const GLuint *) a;
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = (((rawBits[0] >>  0) & 0xff) - 128) / 127.0F;
+               result[1] = (((rawBits[0] >>  8) & 0xff) - 128) / 127.0F;
+               result[2] = (((rawBits[0] >> 16) & 0xff) - 128) / 127.0F;
+               result[3] = (((rawBits[0] >> 24) & 0xff) - 128) / 127.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_UP4UB: /* unpack four GLubytes */
+            {
+               GLfloat a[4], result[4];
+               const GLuint *rawBits = (const GLuint *) a;
+               fetch_vector1( ctx, &inst->SrcReg[0], machine, program, a );
+               result[0] = ((rawBits[0] >>  0) & 0xff) / 255.0F;
+               result[1] = ((rawBits[0] >>  8) & 0xff) / 255.0F;
+               result[2] = ((rawBits[0] >> 16) & 0xff) / 255.0F;
+               result[3] = ((rawBits[0] >> 24) & 0xff) / 255.0F;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_XPD: /* cross product */
+            {
+               GLfloat a[4], b[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               result[0] = a[1] * b[2] - a[2] * b[1];
+               result[1] = a[2] * b[0] - a[0] * b[2];
+               result[2] = a[0] * b[1] - a[1] * b[0];
+               result[3] = 1.0;
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_X2D: /* 2-D matrix transform */
+            {
+               GLfloat a[4], b[4], c[4], result[4];
+               fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a );
+               fetch_vector4( ctx, &inst->SrcReg[1], machine, program, b );
+               fetch_vector4( ctx, &inst->SrcReg[2], machine, program, c );
+               result[0] = a[0] + b[0] * c[0] + b[1] * c[1];
+               result[1] = a[1] + b[0] * c[2] + b[1] * c[3];
+               result[2] = a[2] + b[0] * c[0] + b[1] * c[1];
+               result[3] = a[3] + b[0] * c[2] + b[1] * c[3];
+               store_vector4( inst, machine, result );
+            }
+            break;
+         case OPCODE_PRINT:
+            {
+               if (inst->SrcReg[0].File != -1) {
+                  GLfloat a[4];
+                  fetch_vector4( ctx, &inst->SrcReg[0], machine, program, a);
+                  _mesa_printf("%s%g, %g, %g, %g\n", (const char *) inst->Data,
+                               a[0], a[1], a[2], a[3]);
+               }
+               else {
+                  _mesa_printf("%s\n", (const char *) inst->Data);
+               }
+            }
+            break;
+         case OPCODE_END:
+            return GL_TRUE;
+         default:
+            _mesa_problem(ctx, "Bad opcode %d in _mesa_exec_fragment_program",
+                          inst->Opcode);
+            return GL_TRUE; /* return value doesn't matter */
+
+      }
+      total++;
+      if (total > MAX_EXEC) {
+         _mesa_problem(ctx, "Infinite loop detected in fragment program");
+         return GL_TRUE;
+         abort();
+      }
+   }
+
+#if FEATURE_MESA_program_debug
+   CurrentMachine = NULL;
+#endif
+
+   return GL_TRUE;
+}