src/gallium/auxiliary/tgsi/tgsi_vpos.c

   1 /*
   2  * Copyright 2018 VMware, Inc.
   3  * All Rights Reserved.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the
   7  * "Software"), to deal in the Software without restriction, including
   8  * without limitation the rights to use, copy, modify, merge, publish,
   9  * distribute, sub license, and/or sell copies of the Software, and to
  10  * permit persons to whom the Software is furnished to do so, subject to
  11  * the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the
  14  * next paragraph) shall be included in all copies or substantial portions
  15  * of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  18  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
  20  * IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR
  21  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  22  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  23  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  24  */
  25
  26
  27 /**
  28  * TGSI utility transforms the shader to write imm(0, 0, 0, 1) to vertex
  29  * position
  30  */
  31
  32 #include "util/u_debug.h"
  33 #include "util/u_math.h"
  34 #include "tgsi_vpos.h"
  35 #include "tgsi_transform.h"
  36 #include "tgsi_dump.h"
  37 #include "pipe/p_state.h"
  38
  39
  40 struct write_vpos_context
  41 {
  42    struct tgsi_transform_context base;
  43    unsigned imm_index;
  44 };
  45
  46
  47 static inline struct write_vpos_context *
  48 write_vpos_context(struct tgsi_transform_context *ctx)
  49 {
  50    return (struct write_vpos_context *) ctx;
  51 }
  52
  53
  54 /**
  55  * TGSI transform prolog callback.
  56  */
  57 static void
  58 write_vpos_prolog(struct tgsi_transform_context *ctx)
  59 {
  60    struct write_vpos_context *vc = write_vpos_context(ctx);
  61    struct tgsi_full_instruction inst;
  62
  63    tgsi_transform_immediate_decl(ctx, 0.0, 0.0, 0.0, 1.0);
  64    tgsi_transform_output_decl(ctx, 0,
  65                              TGSI_SEMANTIC_POSITION, 0,
  66                              0);
  67    inst = tgsi_default_full_instruction();
  68    inst.Instruction.Opcode = TGSI_OPCODE_MOV;
  69    inst.Instruction.NumDstRegs = 1;
  70    tgsi_transform_dst_reg(&inst.Dst[0], TGSI_FILE_OUTPUT,
  71                           0, TGSI_WRITEMASK_XYZW);
  72    inst.Instruction.NumSrcRegs = 1;
  73    tgsi_transform_src_reg(&inst.Src[0], TGSI_FILE_IMMEDIATE,
  74                           vc->imm_index, TGSI_SWIZZLE_X,
  75                           TGSI_SWIZZLE_Y, TGSI_SWIZZLE_Z, TGSI_SWIZZLE_W);
  76    ctx->emit_instruction(ctx, &inst);
  77 }
  78
  79
  80 /**
  81  * TGSI utility writes imm(0, 0, 0, 1) to vertex position
  82  */
  83 struct tgsi_token *
  84 tgsi_write_vpos(const struct tgsi_token *tokens_in,
  85                 unsigned num_immediates)
  86 {
  87    struct write_vpos_context transform;
  88    const uint num_new_tokens = 1000; /* should be enough */
  89    const uint new_len = tgsi_num_tokens(tokens_in) + num_new_tokens;
  90    struct tgsi_token *new_tokens;
  91
  92    /* setup transformation context */
  93    memset(&transform, 0, sizeof(transform));
  94    transform.base.prolog = write_vpos_prolog;
  95
  96    transform.imm_index = num_immediates;
  97
  98    /* allocate new tokens buffer */
  99    new_tokens = tgsi_alloc_tokens(new_len);
 100    if (!new_tokens)
 101       return NULL;
 102
 103    /* transform the shader */
 104    tgsi_transform_shader(tokens_in, new_tokens, new_len, &transform.base);
 105
 106    return new_tokens;
 107 }
 108
 109