Created
August 26, 2011 23:47
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Practice Inline ASM on GCC
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#include <assert.h> | |
#include <stdio.h> | |
void in_emu_add(int *z, const int x, const int y) | |
{ | |
*z = x + y; | |
} | |
void in_asm_add(int *z, const int x, const int y) | |
{ | |
__asm__ volatile | |
( | |
"movl %0, %%eax\n\t" | |
"movl %1, %%edx\n\t" | |
"addl %2, %%edx\n\t" | |
"movl %%edx, (%%eax)\n\t" | |
: | |
: "g"(z), "g"(x), "g"(y) | |
: "eax", "edx" | |
); | |
} | |
void test() | |
{ | |
puts(__func__); | |
int a = 1, b = 2, c, d; | |
in_emu_add(&c, a, b); | |
in_asm_add(&d, a, b); | |
printf("c=%d\n", c); | |
printf("d=%d\n", d); | |
assert(c == d); | |
} | |
int main() | |
{ | |
int a = 1, b = 2, c, d; | |
in_emu_add(&c, a, b); | |
in_asm_add(&d, a, b); | |
printf("c=%d\n", c); | |
printf("d=%d\n", d); | |
assert(c == d); | |
test(); | |
return 0; | |
} |
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# Build log | |
$ gcc-mp-4.6 -m32 -std=c99 -O3 -fomit-frame-pointer -Wall -Wextra -S -o add_asm.s add_asm.c | |
$ gcc-mp-4.6 -m32 -std=c99 -O3 -fomit-frame-pointer -Wall -Wextra -S -o add_asm_main.s add_asm_main.c | |
$ gcc-mp-4.6 -m32 -std=c99 -O3 -fomit-frame-pointer -Wall -Wextra -c -o add_asm_main.o add_asm_main.s | |
$ gcc-mp-4.6 -m32 -std=c99 -O3 -fomit-frame-pointer -Wall -Wextra -c -o add_asm.o add_asm.s | |
$ gcc-mp-4.6 -m32 add_asm_main.o add_asm.o -o add_asm_main |
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