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/*
* Copyright © 2010 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 "main/imports.h"
#include "symbol_table.h"
#include "glsl_parser_extras.h"
#include "ast.h"
#include "glsl_types.h"
#include "ir.h"
#define X 1
#define R 5
#define S 9
#define I 13
static bool
generate_swizzle(const char *str, ir_dereference *deref,
unsigned vector_length)
{
/* For each possible swizzle character, this table encodes the value in
* \c idx_map that represents the 0th element of the vector. For invalid
* swizzle characters (e.g., 'k'), a special value is used that will allow
* detection of errors.
*/
static const unsigned char base_idx[26] = {
/* a b c d e f g h i j k l m */
R, R, I, I, I, I, R, I, I, I, I, I, I,
/* n o p q r s t u v w x y z */
I, I, S, S, R, S, S, I, I, X, X, X, X
};
/* Each valid swizzle character has an entry in the previous table. This
* table encodes the base index encoded in the previous table plus the actual
* index of the swizzle character. When processing swizzles, the first
* character in the string is indexed in the previous table. Each character
* in the string is indexed in this table, and the value found there has the
* value form the first table subtracted. The result must be on the range
* [0,3].
*
* For example, the string "wzyx" will get X from the first table. Each of
* the charcaters will get X+3, X+2, X+1, and X+0 from this table. After
* subtraction, the swizzle values are { 3, 2, 1, 0 }.
*
* The string "wzrg" will get X from the first table. Each of the characters
* will get X+3, X+2, R+0, and R+1 from this table. After subtraction, the
* swizzle values are { 3, 2, 4, 5 }. Since 4 and 5 are outside the range
* [0,3], the error is detected.
*/
static const unsigned char idx_map[26] = {
/* a b c d e f g h i j k l m */
R+3, R+2, 0, 0, 0, 0, R+1, 0, 0, 0, 0, 0, 0,
/* n o p q r s t u v w x y z */
0, 0, S+2, S+3, R+0, S+0, S+1, 0, 0, X+3, X+0, X+1, X+2
};
int swiz_idx[4] = { 0, 0, 0, 0 };
unsigned i;
/* Validate the first character in the swizzle string and look up the base
* index value as described above.
*/
if ((str[0] < 'a') || (str[0] > 'z'))
return false;
const unsigned base = base_idx[str[0] - 'a'];
for (i = 0; (i < 4) && (str[i] != '\0'); i++) {
/* Validate the next character, and, as described above, convert it to a
* swizzle index.
*/
if ((str[i] < 'a') || (str[i] > 'z'))
return false;
swiz_idx[i] = idx_map[str[i] - 'a'] - base;
if ((swiz_idx[i] < 0) || (swiz_idx[i] >= (int) vector_length))
return false;
}
if (str[i] != '\0')
return false;
deref->set_swizzle(swiz_idx[0], swiz_idx[1], swiz_idx[2], swiz_idx[3], i);
return true;
}
struct ir_instruction *
_mesa_ast_field_selection_to_hir(const ast_expression *expr,
exec_list *instructions,
struct _mesa_glsl_parse_state *state)
{
ir_instruction *op;
ir_dereference *deref;
YYLTYPE loc;
op = expr->subexpressions[0]->hir(instructions, state);
deref = new ir_dereference(op);
/* Initially assume that the resulting type of the field selection is an
* error. This make the error paths below a bit easier to follow.
*/
deref->type = glsl_error_type;
/* If processing the thing being dereferenced generated an error, bail out
* now. Doing so prevents spurious error messages from being logged below.
*/
if (is_error_type(op->type))
return (struct ir_instruction *) deref;
/* There are two kinds of field selection. There is the selection of a
* specific field from a structure, and there is the selection of a
* swizzle / mask from a vector. Which is which is determined entirely
* by the base type of the thing to which the field selection operator is
* being applied.
*/
loc = expr->get_location();
if (op->type->is_vector()) {
if (generate_swizzle(expr->primary_expression.identifier,
deref, op->type->vector_elements)) {
/* Based on the number of elements in the swizzle and the base type
* (i.e., float, int, unsigned, or bool) of the vector being swizzled,
* generate the type of the resulting value.
*/
deref->type =
glsl_type::get_instance(op->type->base_type,
deref->selector.swizzle.num_components,
1);
} else {
/* FINISHME: Logging of error messages should be moved into
* FINISHME: generate_swizzle. This allows the generation of more
* FINISHME: specific error messages.
*/
_mesa_glsl_error(& loc, state, "Invalid swizzle / mask `%s'",
expr->primary_expression.identifier);
}
} else if (op->type->base_type == GLSL_TYPE_STRUCT) {
/* FINISHME: Handle field selection from structures. */
} else {
_mesa_glsl_error(& loc, state, "Cannot access field `%s' of "
"non-structure / non-vector.",
expr->primary_expression.identifier);
}
return (struct ir_instruction *) deref;
}
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