[Vm-dev] ARM Cogit

[tim Rowledge]

And this code (pulled from the Pi forum, written by ???) demonstrates - 
#include <stdio.h>
#include <sys/mman.h>
#include <stdint.h>
#include <stdlib.h>

int inc(int x){ //increments x

    uint32_t *ret = mmap(NULL,
            2 * sizeof(uint32_t),  // Space for 16 instructions. (More than enough.)
            PROT_READ | PROT_WRITE | PROT_EXEC,
            MAP_PRIVATE | MAP_ANONYMOUS,
            -1,0);
    if (ret == MAP_FAILED) {
        printf("Could not mmap a memory buffer with the proper permissions.\n");
        return -1;
    }

    *(ret + 0) = 0xE2800001; //add r0 r0 #1 := r0 += 1
    *(ret + 1) = 0xE12FFF1E; //bx lr        := jump back to inc()

    __clear_cache((char*) ret, (char*) (ret+2));

    int(*f)(int) = (int (*)(int)) ret;
    return (*f)(x);
}

int main(){
    printf("%d\n",inc(6)); //expect '7' to be printed
exit(0);}

tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Strange OpCodes: YVR: Branch to Vancouver