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Better exp algorithm from divVerent

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This commit is contained in:
Dale Weiler 2013-11-23 12:45:22 -05:00
parent 52cda620b2
commit 23904bad52
1 changed files with 90 additions and 29 deletions
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119
intrin.c
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@ -58,7 +58,6 @@ static GMQCC_INLINE void intrin_reg(intrin_t *intrin, ast_value *const value, as
vec_push(intrin->parser->globals, (ast_expression*)value);
}
#define QC_M_E 2.718281828459045f
#define QC_POW_EPSILON 0.00001f
/*
@ -622,45 +621,107 @@ static ast_expression *intrin_mod(intrin_t *intrin) {
static ast_expression *intrin_exp(intrin_t *intrin) {
/*
* float exp(float x) {
* // mul 10 to round increments of 0.1f
* return floor((pow(QC_M_E, x) * 10) + 0.5) / 10;
* float sum = 1.0;
* float acc = 1.0;
* float i;
* for (i = 1; i < 200; ++i)
* sum += (acc *= x / i);
*
* return sum;
* }
*/
ast_value *value = NULL;
ast_call *callpow = ast_call_new (intrin_ctx(intrin), intrin_func_self(intrin, "pow", "exp"));
ast_call *callfloor = ast_call_new (intrin_ctx(intrin), intrin_func_self(intrin, "floor", "exp"));
ast_value *arg1 = ast_value_new(intrin_ctx(intrin), "x", TYPE_FLOAT);
ast_block *body = ast_block_new(intrin_ctx(intrin));
ast_function *func = intrin_value(intrin, &value, "exp", TYPE_FLOAT);
ast_value *value = NULL;
ast_value *x = ast_value_new(intrin_ctx(intrin), "x", TYPE_FLOAT);
ast_value *sum = ast_value_new(intrin_ctx(intrin), "sum", TYPE_FLOAT);
ast_value *acc = ast_value_new(intrin_ctx(intrin), "acc", TYPE_FLOAT);
ast_value *i = ast_value_new(intrin_ctx(intrin), "i", TYPE_FLOAT);
ast_block *body = ast_block_new(intrin_ctx(intrin));
ast_function *func = intrin_value(intrin, &value, "mexp", TYPE_FLOAT);
vec_push(value->expression.params, arg1);
vec_push(value->expression.params, x);
vec_push(body->locals, sum);
vec_push(body->locals, acc);
vec_push(body->locals, i);
vec_push(callpow->params, (ast_expression*)fold_constgen_float(intrin->fold, QC_M_E));
vec_push(callpow->params, (ast_expression*)arg1);
vec_push(callfloor->params,
(ast_expression*)ast_binary_new(
/* sum = 1.0; */
vec_push(body->exprs,
(ast_expression*)ast_store_new(
intrin_ctx(intrin),
INSTR_ADD_F,
(ast_expression*)ast_binary_new(
intrin_ctx(intrin),
INSTR_MUL_F,
(ast_expression*)callpow,
(ast_expression*)fold_constgen_float(intrin->fold, 10.0f)
),
(ast_expression*)fold_constgen_float(intrin->fold, 0.5f)
INSTR_STORE_F,
(ast_expression*)sum,
(ast_expression*)intrin->fold->imm_float[1]
)
);
/* return <callfloor> / 10.0f */
/* acc = 1.0; */
vec_push(body->exprs,
(ast_expression*)ast_store_new(
intrin_ctx(intrin),
INSTR_STORE_F,
(ast_expression*)acc,
(ast_expression*)intrin->fold->imm_float[1]
)
);
/*
* for (i = 1; i < 200; ++i)
* sum += (acc *= x / i);
*/
vec_push(body->exprs,
(ast_expression*)ast_loop_new(
intrin_ctx(intrin),
/* i = 1; */
(ast_expression*)ast_store_new(
intrin_ctx(intrin),
INSTR_STORE_F,
(ast_expression*)i,
(ast_expression*)intrin->fold->imm_float[1]
),
/* i < 200; */
(ast_expression*)ast_binary_new(
intrin_ctx(intrin),
INSTR_LT,
(ast_expression*)i,
(ast_expression*)fold_constgen_float(intrin->fold, 200.0f)
),
false,
NULL,
false,
/* ++i; */
(ast_expression*)ast_binstore_new(
intrin_ctx(intrin),
INSTR_STORE_F,
INSTR_ADD_F,
(ast_expression*)i,
(ast_expression*)intrin->fold->imm_float[1]
),
/* sum += (acc *= (x / i)) */
(ast_expression*)ast_binstore_new(
intrin_ctx(intrin),
INSTR_STORE_F,
INSTR_ADD_F,
(ast_expression*)sum,
(ast_expression*)ast_binstore_new(
intrin_ctx(intrin),
INSTR_STORE_F,
INSTR_MUL_F,
(ast_expression*)acc,
(ast_expression*)ast_binary_new(
intrin_ctx(intrin),
INSTR_DIV_F,
(ast_expression*)x,
(ast_expression*)i
)
)
)
)
);
/* return sum; */
vec_push(body->exprs,
(ast_expression*)ast_return_new(
intrin_ctx(intrin),
(ast_expression*)ast_binary_new(
intrin_ctx(intrin),
INSTR_DIV_F,
(ast_expression*)callfloor,
(ast_expression*)fold_constgen_float(intrin->fold, 10.0f)
)
(ast_expression*)sum
)
);