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// gcc -mfpmath=387 -o test32 test32.c -lm
#include <stdio.h>
#include <stdint.h>
#include <math.h>
volatile double test_values[] = {
3.0, 2.0, 0.1
};
#define TEST_X87(INSN_LOAD, INSN_OP, VAL_IDX) \
do { \
volatile double result; \
volatile double* val_ptr = &test_values[VAL_IDX]; \
__asm__ volatile( \
"fldcw %[low]\n\t" INSN_LOAD "\n\t" INSN_OP "\n\t" \
"fstl %[res]\n\t" \
"fldcw %[orig]\n\t" \
: [res] "=m"(result) \
: [low] "m"(low_cw), \
[orig] "m"(original_cw), \
[val] "m"(*val_ptr) \
: "st", "st(1)"); \
printf("%-16s: %016lx\n", #INSN_OP, *(uint64_t*)&result); \
} while (0)
uint16_t original_cw, low_cw;
int main()
{
__asm__ volatile("fstcw %0" : "=m"(original_cw));
low_cw = original_cw & ~((uint16_t)0x0300);
TEST_X87("fld1; fldl %3", "fdivrp", 0); // 1.0 / 3.0
TEST_X87("fldl %3", "fsqrt", 1); // sqrt(2.0)
TEST_X87("fldl %3; fldl %3", "faddp", 2); // 0.1 + 0.1
return 0;
}
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