/*
 * Copyright © 2016 Intel Corporation
 *
 * 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 (including the next
 * paragraph) 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
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 */

#include <stdio.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdarg.h>
#include <string.h>
#include <expat.h>

#include <util/macros.h>

#include "decoder.h"

#define XML_BUFFER_SIZE 4096

#define MAKE_GEN(major, minor) ( ((major) << 8) | (minor) )

struct gen_spec {
   uint32_t gen;

   int ncommands;
   struct gen_group *commands[256];
   int nstructs;
   struct gen_group *structs[256];
   int nregisters;
   struct gen_group *registers[256];
};

struct location {
   const char *filename;
   int line_number;
};

struct parser_context {
   XML_Parser parser;
   int foo;
   struct location loc;
   const char *platform;

   struct gen_group *group;

   int nfields;
   struct gen_field *fields[128];

   struct gen_spec *spec;
};

const char *
gen_group_get_name(struct gen_group *group)
{
   return group->name;
}

uint32_t
gen_group_get_opcode(struct gen_group *group)
{
   return group->opcode;
}

struct gen_group *
gen_spec_find_struct(struct gen_spec *spec, const char *name)
{
   for (int i = 0; i < spec->nstructs; i++)
      if (strcmp(spec->structs[i]->name, name) == 0)
         return spec->structs[i];

   return NULL;
}

uint32_t
gen_spec_get_gen(struct gen_spec *spec)
{
   return spec->gen;
}

static void __attribute__((noreturn))
fail(struct location *loc, const char *msg, ...)
{
   va_list ap;

   va_start(ap, msg);
   fprintf(stderr, "%s:%d: error: ",
           loc->filename, loc->line_number);
   vfprintf(stderr, msg, ap);
   fprintf(stderr, "\n");
   va_end(ap);
   exit(EXIT_FAILURE);
}

static void *
fail_on_null(void *p)
{
   if (p == NULL) {
      fprintf(stderr, "aubinator: out of memory\n");
      exit(EXIT_FAILURE);
   }

   return p;
}

static char *
xstrdup(const char *s)
{
   return fail_on_null(strdup(s));
}

static void *
zalloc(size_t s)
{
   return calloc(s, 1);
}

static void *
xzalloc(size_t s)
{
   return fail_on_null(zalloc(s));
}

static struct gen_group *
create_group(struct parser_context *ctx, const char *name, const char **atts)
{
   struct gen_group *group;

   group = xzalloc(sizeof(*group));
   if (name)
      group->name = xstrdup(name);

   group->group_offset = 0;
   group->group_count = 0;

   return group;
}

static void
get_group_offset_count(struct parser_context *ctx, const char *name, const char **atts, uint32_t *offset, uint32_t *count)
{
   char *p;
   int i;

   for (i = 0; atts[i]; i += 2) {
      if (strcmp(atts[i], "count") == 0)
         *count = strtoul(atts[i + 1], &p, 0);
      else if (strcmp(atts[i], "start") == 0)
         *offset = strtoul(atts[i + 1], &p, 0);
   }
   return;
}

static inline uint64_t
mask(int start, int end)
{
   uint64_t v;

   v = ~0ULL >> (63 - end + start);

   return v << start;
}

static inline uint64_t
field(uint64_t value, int start, int end)
{
   /* The field values are obtained from the DWord,
    * Hence, get the relative start and end positions
    * by doing a %32 on the start and end positions
    */
   return (value & mask(start % 32, end % 32)) >> (start % 32);
}

static inline uint64_t
field_address(uint64_t value, int start, int end)
{
   /* no need to right shift for address/offset */
   return (value & mask(start % 32, end % 32));
}

static struct gen_type
string_to_type(struct parser_context *ctx, const char *s)
{
   int i, f;
   struct gen_group *g;

   if (strcmp(s, "int") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_INT };
   else if (strcmp(s, "uint") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_UINT };
   else if (strcmp(s, "bool") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_BOOL };
   else if (strcmp(s, "float") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_FLOAT };
   else if (strcmp(s, "address") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_ADDRESS };
   else if (strcmp(s, "offset") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_OFFSET };
   else if (sscanf(s, "u%d.%d", &i, &f) == 2)
      return (struct gen_type) { .kind = GEN_TYPE_UFIXED, .i = i, .f = f };
   else if (sscanf(s, "s%d.%d", &i, &f) == 2)
      return (struct gen_type) { .kind = GEN_TYPE_SFIXED, .i = i, .f = f };
   else if (g = gen_spec_find_struct(ctx->spec, s), g != NULL)
      return (struct gen_type) { .kind = GEN_TYPE_STRUCT, .gen_struct = g };
   else if (strcmp(s, "mbo") == 0)
      return (struct gen_type) { .kind = GEN_TYPE_MBO };
   else
      fail(&ctx->loc, "invalid type: %s", s);
}

static struct gen_field *
create_field(struct parser_context *ctx, const char **atts)
{
   struct gen_field *field;
   char *p;
   int i;

   field = xzalloc(sizeof(*field));

   for (i = 0; atts[i]; i += 2) {
      if (strcmp(atts[i], "name") == 0)
         field->name = xstrdup(atts[i + 1]);
      else if (strcmp(atts[i], "start") == 0)
         field->start = ctx->group->group_offset+strtoul(atts[i + 1], &p, 0);
      else if (strcmp(atts[i], "end") == 0) {
         field->end = ctx->group->group_offset+strtoul(atts[i + 1], &p, 0);
         if(ctx->group->group_offset)
            ctx->group->group_offset = field->end+1;
      } else if (strcmp(atts[i], "type") == 0)
         field->type = string_to_type(ctx, atts[i + 1]);
      else if (strcmp(atts[i], "default") == 0 &&
               field->start >= 16 && field->end <= 31) {
         field->has_default = true;
         field->default_value = strtoul(atts[i + 1], &p, 0);
      }
   }

   return field;
}

static void
start_element(void *data, const char *element_name, const char **atts)
{
   struct parser_context *ctx = data;
   int i;
   const char *name = NULL;
   const char *gen = NULL;

   ctx->loc.line_number = XML_GetCurrentLineNumber(ctx->parser);

   for (i = 0; atts[i]; i += 2) {
      if (strcmp(atts[i], "name") == 0)
         name = atts[i + 1];
      else if (strcmp(atts[i], "gen") == 0)
         gen = atts[i + 1];
   }

   if (strcmp(element_name, "genxml") == 0) {
      if (name == NULL)
         fail(&ctx->loc, "no platform name given");
      if (gen == NULL)
         fail(&ctx->loc, "no gen given");

      ctx->platform = xstrdup(name);
      int major, minor;
      int n = sscanf(gen, "%d.%d", &major, &minor);
      if (n == 0)
         fail(&ctx->loc, "invalid gen given: %s", gen);
      if (n == 1)
         minor = 0;

      ctx->spec->gen = MAKE_GEN(major, minor);
   } else if (strcmp(element_name, "instruction") == 0 ||
              strcmp(element_name, "struct") == 0 ||
              strcmp(element_name, "register") == 0) {
      ctx->group = create_group(ctx, name, atts);
   } else if (strcmp(element_name, "group") == 0) {
      get_group_offset_count(ctx, name, atts,&ctx->group->group_offset,&ctx->group->group_count);
   } else if (strcmp(element_name, "field") == 0) {
      do {
         ctx->fields[ctx->nfields++] = create_field(ctx, atts);
         if(ctx->group->group_count)
            ctx->group->group_count--;
      } while (ctx->group->group_count > 0);
   } else if (strcmp(element_name, "enum") == 0) {
   } else if (strcmp(element_name, "value") == 0) {
   }
}

static void
end_element(void *data, const char *name)
{
   struct parser_context *ctx = data;

   if (strcmp(name, "instruction") == 0 ||
      strcmp(name, "struct") == 0 ||
      strcmp(name, "register") == 0) {
      size_t size = ctx->nfields * sizeof(ctx->fields[0]);
      struct gen_group *group = ctx->group;

      group->fields = xzalloc(size);
      group->nfields = ctx->nfields;
      memcpy(group->fields, ctx->fields, size);
      ctx->nfields = 0;
      ctx->group = NULL;

      for (int i = 0; i < group->nfields; i++) {
         if (group->fields[i]->start >= 16 &&
            group->fields[i]->end <= 31 &&
            group->fields[i]->has_default) {
            group->opcode_mask |=
               mask(group->fields[i]->start % 32, group->fields[i]->end % 32);
            group->opcode |=
               group->fields[i]->default_value << group->fields[i]->start;
         }
      }

      struct gen_spec *spec = ctx->spec;
      if (strcmp(name, "instruction") == 0)
         spec->commands[spec->ncommands++] = group;
      else if (strcmp(name, "struct") == 0)
         spec->structs[spec->nstructs++] = group;
      else if (strcmp(name, "register") == 0)
         spec->registers[spec->nregisters++] = group;
   } else if (strcmp(name, "group") == 0) {
      ctx->group->group_offset = 0;
      ctx->group->group_count = 0;
   }
}

static void
character_data(void *data, const XML_Char *s, int len)
{
}

struct gen_spec *
gen_spec_load(const char *filename)
{
   struct parser_context ctx;
   void *buf;
   int len;
   FILE *input;

   input = fopen(filename, "r");
   printf("xml filename = %s\n", filename);
   if (input == NULL) {
      fprintf(stderr, "failed to open xml description\n");
      exit(EXIT_FAILURE);
   }

   memset(&ctx, 0, sizeof ctx);
   ctx.parser = XML_ParserCreate(NULL);
   XML_SetUserData(ctx.parser, &ctx);
   if (ctx.parser == NULL) {
      fprintf(stderr, "failed to create parser\n");
      fclose(input);
      return NULL;
   }

   XML_SetElementHandler(ctx.parser, start_element, end_element);
   XML_SetCharacterDataHandler(ctx.parser, character_data);
   ctx.loc.filename = filename;

   ctx.spec = xzalloc(sizeof(*ctx.spec));

   do {
      buf = XML_GetBuffer(ctx.parser, XML_BUFFER_SIZE);
      len = fread(buf, 1, XML_BUFFER_SIZE, input);
      if (len < 0) {
         fprintf(stderr, "fread: %m\n");
         fclose(input);
         return NULL;
      }
      if (XML_ParseBuffer(ctx.parser, len, len == 0) == 0) {
         fprintf(stderr,
                 "Error parsing XML at line %ld col %ld: %s\n",
                 XML_GetCurrentLineNumber(ctx.parser),
                 XML_GetCurrentColumnNumber(ctx.parser),
                 XML_ErrorString(XML_GetErrorCode(ctx.parser)));
         fclose(input);
         return NULL;
      }
   } while (len > 0);

   XML_ParserFree(ctx.parser);
   fclose(input);

   return ctx.spec;
}

struct gen_group *
gen_spec_find_instruction(struct gen_spec *spec, const uint32_t *p)
{
   for (int i = 0; i < spec->ncommands; i++) {
      uint32_t opcode = *p & spec->commands[i]->opcode_mask;
      if (opcode == spec->commands[i]->opcode)
         return spec->commands[i];
   }

   return NULL;
}

int
gen_group_get_length(struct gen_group *group, const uint32_t *p)
{
   uint32_t h = p[0];
   uint32_t type = field(h, 29, 31);

   switch (type) {
   case 0: /* MI */ {
      uint32_t opcode = field(h, 23, 28);
      if (opcode < 16)
         return 1;
      else
         return field(h, 0, 7) + 2;
      break;
   }

   case 3: /* Render */ {
      uint32_t subtype = field(h, 27, 28);
      switch (subtype) {
      case 0:
         return field(h, 0, 7) + 2;
      case 1:
         return 1;
      case 2:
         return 2;
      case 3:
         return field(h, 0, 7) + 2;
      }
   }
   }

   unreachable("bad opcode");
}

void
gen_field_iterator_init(struct gen_field_iterator *iter,
                        struct gen_group *group, const uint32_t *p)
{
   iter->group = group;
   iter->p = p;
   iter->i = 0;
}

bool
gen_field_iterator_next(struct gen_field_iterator *iter)
{
   struct gen_field *f;
   union {
      uint32_t dw;
      float f;
   } v;

   if (iter->i == iter->group->nfields)
      return false;

   f = iter->group->fields[iter->i++];
   iter->name = f->name;
   v.dw = iter->p[f->start / 32];
   switch (f->type.kind) {
   case GEN_TYPE_UNKNOWN:
   case GEN_TYPE_INT:
      snprintf(iter->value, sizeof(iter->value),
               "%ld", field(v.dw, f->start, f->end));
      break;
   case GEN_TYPE_UINT:
      snprintf(iter->value, sizeof(iter->value),
               "%lu", field(v.dw, f->start, f->end));
      break;
   case GEN_TYPE_BOOL:
      snprintf(iter->value, sizeof(iter->value),
               "%s", field(v.dw, f->start, f->end) ? "true" : "false");
      break;
   case GEN_TYPE_FLOAT:
      snprintf(iter->value, sizeof(iter->value), "%f", v.f);
      break;
   case GEN_TYPE_ADDRESS:
   case GEN_TYPE_OFFSET:
      snprintf(iter->value, sizeof(iter->value),
               "0x%08lx", field_address(v.dw, f->start, f->end));
      break;
   case GEN_TYPE_STRUCT:
      snprintf(iter->value, sizeof(iter->value),
               "<struct %s %d>", f->type.gen_struct->name, (f->start / 32));
      break;
   case GEN_TYPE_UFIXED:
      snprintf(iter->value, sizeof(iter->value),
               "%f", (float) field(v.dw, f->start, f->end) / (1 << f->type.f));
      break;
   case GEN_TYPE_SFIXED:
      /* FIXME: Sign extend extracted field. */
      snprintf(iter->value, sizeof(iter->value), "%s", "foo");
      break;
   case GEN_TYPE_MBO:
       break;
   }

   return true;
}