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Archive for July, 2009

[业余土制] 实时汇编编译器

July 5th, 2009 3 comments

实时动态在内存中编译汇编代码,并返回函数调用指针,可用于JIT系统的后端:

项目地址:http://code.google.com/p/asmpure/

例子:

const char *AlphaBlendAsm =
"PROC C1:DWORD, C2:DWORD, A:DWORD\n"
"    movd mm0, A\n"
"    punpcklwd mm0, mm0\n"
"    punpckldq mm0, mm0\n"
"    pcmpeqb mm7, mm7\n"
"    psubw mm7, mm0\n"
"    \n"
"    punpcklbw mm1, C1\n"
"    psrlw mm1, 8\n"
"    punpcklbw mm2, C2\n"
"    psrlw mm2, 8\n"
"    \n"
"    pmullw mm1, mm7\n"
"    pmullw mm2, mm0\n"
"    paddw mm1, mm2\n"
"    \n"
"    psrlw mm1, 8\n"
"    packuswb mm1, mm1\n"
"    movd eax, mm1\n"
"    emms\n"
"    ret\n"
"ENDP\n";

void testAlphaBlend(void)
{
        CAssembler *casm;
        int c;

        int (*AlphaBlendPtr)(int, int, int);

        // create assembler
        casm = casm_create();

        // append assembly source
        casm_source(casm, AlphaBlendAsm);

        AlphaBlendPtr = (int (*)(int, int, int))casm_callable(casm, NULL);

        if (AlphaBlendPtr == NULL) {
                printf("error: %s\n", casm->error);
                casm_release(casm);
                return;
        }

        printf("==================== Alpha Blend ====================\n");

        casm_dumpinst(casm, stdout);

        printf("\nExecute code (y/n)?\n\n");

        do
        {
                c = getch();
        }
        while(c != 'y' && c != 'n');

        if(c == 'y')
        {
                int x = AlphaBlendPtr(0x00FF00FF, 0xFF00FF00, 128);
                printf("output: %.8X\n\n", x);
        }

        free(AlphaBlendPtr);
        casm_release(casm);
}

output: 7f7f7f7f