hi everybody, do anybody know how can i write assembly code on iphone device?
i read some documentation for assembly, however when i tried to code simple ex: addition 2 integer number :
__asm__("add %1, %0" : "=r"(y) : "r"(a), "r" (b));
it will work well on simulator, however it does not work on device when i try to deploy to device, it seem that no such information about this addition command.
ok, tried other command:
inline int asm_saturate_to_255 (int a) {
int y;
__asm__("usat %0, #8, %1\n\t" : "=r"(y) : "r"(a));
return y;
}
oh, it will work on device however not work on simulator, and i can't find reference of "usat" command
anybody can help me?
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by: Infinity08Posted on 2009-06-02 at 23:32:25ID: 24533756
>> and i can't find reference of "usat" command
That's part of the ARM instruction set (iPhone's CPU is an ARM CPU afaik). If you type in "ARM instruction set quick reference" in Google, you should get some good results ...
>> __asm__("add %1, %0" : "=r"(y) : "r"(a), "r" (b));
That looks like x86 assembly. The ARM add instruction takes 3 parameters.
>> oh, it will work on device however not work on simulator
The iPhone simulator runs x86 code afaik, not ARM code (it doesn't emulate the iPhone hardware, just simulates it). This is why it didn't work on your simulator, but worked on the phone itself.
You could always use an #if to check whether you're compiling for the simulator or for the phone, and generate different code for each.