/*
 * Copyright 2012 Advanced Micro Devices, Inc.
 * Author: Tom Stellard <thomas.stellard@amd.com>
 * SPDX-License-Identifier: MIT
 */

#include <stdio.h>
#include "util/u_bitcast.h"
#include "radeon_compiler.h"
#include "radeon_compiler_util.h"
#include "radeon_dataflow.h"
#include "radeon_program.h"
#include "radeon_program_constants.h"
#include "radeon_swizzle.h"

#define VERBOSE 0

#define DBG(...)                                                                                   \
   do {                                                                                            \
      if (VERBOSE)                                                                                 \
         fprintf(stderr, __VA_ARGS__);                                                             \
   } while (0)

/* IEEE-754:
 * 22:0 mantissa
 * 30:23 exponent
 * 31 sign
 *
 * R300:
 * 0:2 mantissa
 * 3:6 exponent (bias 7)
 */
static int
ieee_754_to_r300_float(float f, unsigned char *r300_float_out)
{
   unsigned float_bits = u_bitcast_f2u(f);
   /* XXX: Handle big-endian */
   unsigned mantissa = float_bits & 0x007fffff;
   unsigned biased_exponent = (float_bits & 0x7f800000) >> 23;
   unsigned negate = !!(float_bits & 0x80000000);
   int exponent = biased_exponent - 127;
   unsigned mantissa_mask = 0xff8fffff;
   unsigned r300_exponent, r300_mantissa;

   DBG("Converting %f (0x%x) to 7-bit:\n", f, float_bits);
   DBG("Raw exponent = %d\n", exponent);

   if (exponent < -7 || exponent > 8) {
      DBG("Failed exponent out of range\n\n");
      return 0;
   }

   if (mantissa & mantissa_mask) {
      DBG("Failed mantissa has too many bits:\n"
          "mantissa=0x%x mantissa_mask=0x%x, and=0x%x\n\n",
          mantissa, mantissa_mask, mantissa & mantissa_mask);
      return 0;
   }

   r300_exponent = exponent + 7;
   r300_mantissa = (mantissa & ~mantissa_mask) >> 20;
   *r300_float_out = r300_mantissa | (r300_exponent << 3);

   DBG("Success! r300_float = 0x%x\n\n", *r300_float_out);

   if (negate)
      return -1;
   else
      return 1;
}

void
rc_inline_literals(struct radeon_compiler *c, void *user)
{
   struct rc_instruction *inst;

   for (inst = c->Program.Instructions.Next; inst != &c->Program.Instructions; inst = inst->Next) {
      const struct rc_opcode_info *info = rc_get_opcode_info(inst->U.I.Opcode);

      unsigned src_idx;
      struct rc_constant *constant;
      float float_value;
      unsigned char r300_float = 0;
      int ret;

      /* XXX: Handle presub */

      /* We aren't using rc_for_all_reads_src here, because presub
       * sources need to be handled differently. */
      for (src_idx = 0; src_idx < info->NumSrcRegs; src_idx++) {
         unsigned use_literal = 0;
         unsigned swz, chan;
         struct rc_src_register src_reg = inst->U.I.SrcReg[src_idx];
         if (src_reg.File != RC_FILE_CONSTANT) {
            continue;
         }
         constant = &c->Program.Constants.Constants[src_reg.Index];
         if (constant->Type != RC_CONSTANT_IMMEDIATE) {
            continue;
         }
         for (chan = 0; chan < 4; chan++) {
            unsigned char r300_float_tmp;
            swz = GET_SWZ(src_reg.Swizzle, chan);
            if (swz >= RC_SWIZZLE_ZERO) {
               continue;
            }
            float_value = constant->u.Immediate[swz];
            ret = ieee_754_to_r300_float(float_value, &r300_float_tmp);
            if (!ret || (use_literal && r300_float != r300_float_tmp)) {
               use_literal = 0;
               break;
            }

            if (ret == -1 && src_reg.Abs) {
               use_literal = 0;
               break;
            }

            if (!use_literal) {
               r300_float = r300_float_tmp;
               use_literal = 1;
            }

            /* We can use any swizzle, so if this is ADD it might
             * be smart to us the same swizzle as the other src uses
             * so that we potentially enable presubtract later.
             * Use RC_SWIZZLE_W otherwise, so it will become one of
             * the alpha sources.
             */
            if (info->Opcode == RC_OPCODE_ADD &&
                GET_SWZ(inst->U.I.SrcReg[1 - src_idx].Swizzle, chan) == chan) {
               SET_SWZ(src_reg.Swizzle, chan, chan);
            } else {
               SET_SWZ(src_reg.Swizzle, chan, RC_SWIZZLE_W);
            }
            if (ret == -1) {
               src_reg.Negate ^= (1 << chan);
            }
         }

         src_reg.File = RC_FILE_INLINE;
         src_reg.Index = r300_float;
         if (!use_literal || !c->SwizzleCaps->IsNative(inst->U.I.Opcode, src_reg)) {
            continue;
         }
         inst->U.I.SrcReg[src_idx] = src_reg;
      }
   }
}