diff options
Diffstat (limited to 'src/mesa/main/imports.c')
| -rw-r--r-- | src/mesa/main/imports.c | 148 |
1 files changed, 0 insertions, 148 deletions
diff --git a/src/mesa/main/imports.c b/src/mesa/main/imports.c index 350e6752c8b..230ebbc67f4 100644 --- a/src/mesa/main/imports.c +++ b/src/mesa/main/imports.c @@ -307,154 +307,6 @@ _mesa_bitcount_64(uint64_t n) } #endif - -/** - * Convert a 4-byte float to a 2-byte half float. - * - * Not all float32 values can be represented exactly as a float16 value. We - * round such intermediate float32 values to the nearest float16. When the - * float32 lies exactly between to float16 values, we round to the one with - * an even mantissa. - * - * This rounding behavior has several benefits: - * - It has no sign bias. - * - * - It reproduces the behavior of real hardware: opcode F32TO16 in Intel's - * GPU ISA. - * - * - By reproducing the behavior of the GPU (at least on Intel hardware), - * compile-time evaluation of constant packHalf2x16 GLSL expressions will - * result in the same value as if the expression were executed on the GPU. - */ -GLhalfARB -_mesa_float_to_half(float val) -{ - const fi_type fi = {val}; - const int flt_m = fi.i & 0x7fffff; - const int flt_e = (fi.i >> 23) & 0xff; - const int flt_s = (fi.i >> 31) & 0x1; - int s, e, m = 0; - GLhalfARB result; - - /* sign bit */ - s = flt_s; - - /* handle special cases */ - if ((flt_e == 0) && (flt_m == 0)) { - /* zero */ - /* m = 0; - already set */ - e = 0; - } - else if ((flt_e == 0) && (flt_m != 0)) { - /* denorm -- denorm float maps to 0 half */ - /* m = 0; - already set */ - e = 0; - } - else if ((flt_e == 0xff) && (flt_m == 0)) { - /* infinity */ - /* m = 0; - already set */ - e = 31; - } - else if ((flt_e == 0xff) && (flt_m != 0)) { - /* NaN */ - m = 1; - e = 31; - } - else { - /* regular number */ - const int new_exp = flt_e - 127; - if (new_exp < -14) { - /* The float32 lies in the range (0.0, min_normal16) and is rounded - * to a nearby float16 value. The result will be either zero, subnormal, - * or normal. - */ - e = 0; - m = _mesa_lroundevenf((1 << 24) * fabsf(fi.f)); - } - else if (new_exp > 15) { - /* map this value to infinity */ - /* m = 0; - already set */ - e = 31; - } - else { - /* The float32 lies in the range - * [min_normal16, max_normal16 + max_step16) - * and is rounded to a nearby float16 value. The result will be - * either normal or infinite. - */ - e = new_exp + 15; - m = _mesa_lroundevenf(flt_m / (float) (1 << 13)); - } - } - - assert(0 <= m && m <= 1024); - if (m == 1024) { - /* The float32 was rounded upwards into the range of the next exponent, - * so bump the exponent. This correctly handles the case where f32 - * should be rounded up to float16 infinity. - */ - ++e; - m = 0; - } - - result = (s << 15) | (e << 10) | m; - return result; -} - - -/** - * Convert a 2-byte half float to a 4-byte float. - * Based on code from: - * http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html - */ -float -_mesa_half_to_float(GLhalfARB val) -{ - /* XXX could also use a 64K-entry lookup table */ - const int m = val & 0x3ff; - const int e = (val >> 10) & 0x1f; - const int s = (val >> 15) & 0x1; - int flt_m, flt_e, flt_s; - fi_type fi; - float result; - - /* sign bit */ - flt_s = s; - - /* handle special cases */ - if ((e == 0) && (m == 0)) { - /* zero */ - flt_m = 0; - flt_e = 0; - } - else if ((e == 0) && (m != 0)) { - /* denorm -- denorm half will fit in non-denorm single */ - const float half_denorm = 1.0f / 16384.0f; /* 2^-14 */ - float mantissa = ((float) (m)) / 1024.0f; - float sign = s ? -1.0f : 1.0f; - return sign * mantissa * half_denorm; - } - else if ((e == 31) && (m == 0)) { - /* infinity */ - flt_e = 0xff; - flt_m = 0; - } - else if ((e == 31) && (m != 0)) { - /* NaN */ - flt_e = 0xff; - flt_m = 1; - } - else { - /* regular */ - flt_e = e + 112; - flt_m = m << 13; - } - - fi.i = (flt_s << 31) | (flt_e << 23) | flt_m; - result = fi.f; - return result; -} - /*@}*/ |