Hell Oh Entropy!

Life, Code and everything in between

My first program on my Samsung Galaxy S

Posted: Aug 21, 2011, 16:17

No, it is not a java program, it is in assembly, which was possible because I recently flashed Cyanogenmod on my phone. Here it is:

.text
.global _start
_start:
    mov r7, #1
    mov r0, #42
    swi #0

The program simply returns 42 and exits. I used my own cross-built binutils (--target=armv-android-eabi) to build this and simply copied it over to my phone, chmod and executed it. You need to put it outside your sdcard environment however, since you cannot execute anything in /sdcard. A Stackoverflow thread helped figure out the right opcode for the syscall.

It took me all of 6 hours to figure this out. 5 minutes to figure out the above code and 5 hours and 55 minutes to realize and fix the last line from

swi 0

to

swi #0

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