ARM Assembly for eVC with the Mono Jit Macros

#include <windows.h>
#include <stdio.h>
#include <arm-codegen.h>
#include <arm-dis.h>


unsigned long fib_c(unsigned long n) {
if (n < 2)
	return(1);
else
	return(fib_c(n-2) + fib_c(n-1));
}


void setup_fib_jit (unsigned int *pins) {

/* label1 */
ARM_CMP_REG_IMM8 (pins, ARMREG_R0, 2); /* is n < 2 ? */
ARM_MOV_REG_IMM8_COND (pins, ARMREG_R0, 1, ARMCOND_LO); /* if yes return value is 1 */
ARM_MOV_REG_REG_COND (pins, ARMREG_PC,  ARMREG_LR, ARMCOND_LO);
                                        /* if yes return address in PC; */
                                        /* and exit to main or previous recursive call */
ARM_PUSH2 (pins, ARMREG_R0, ARMREG_LR); /* save n and return address to the stack*/
ARM_SUB_REG_IMM8(pins, ARMREG_R0, ARMREG_R0, 2); /* n = n-2 */
ARM_BL (pins, -7); /* recurse to label1 for fib(n-2) */

ARM_LDR_IMM (pins, ARMREG_R1, ARMREG_SP, 0); /* load n from the stack */
ARM_STR_IMM (pins, ARMREG_R0, ARMREG_SP, 0); /* store result fib(n-2) */

ARM_SUB_REG_IMM8(pins, ARMREG_R0, ARMREG_R1, 1); /* n = n-1 */
ARM_BL (pins, -11); /* recurse to label1 for fib(n-1) */
ARM_POP2 (pins, ARMREG_R1, ARMREG_LR); /* pop result fib(n-2) and return address */

ARM_ADD_REG_REG (pins, ARMREG_R0, ARMREG_R0, ARMREG_R1); /* add both results */

ARM_MOV_REG_REG (pins, ARMREG_PC,  ARMREG_LR);
                                        /* return address in PC; */
                                        /* and exit to main or previous recursive call */
}


int main (int argc, char *argv[]) {

UINT32 n, ins[500], *pins = ins;
unsigned long (*fib_jit)(int n) = (unsigned long (*)(int n)) ins;
unsigned long r1, r2, t0, t1, t2;


setup_fib_jit (pins);
_armdis_dump (stdout, ins, 52);

if (argc <= 2) {
	if (argc == 1)
		n=1;
	else
		n=atoi (argv[1]);
t0 = GetTickCount();
r1 = fib_c (n);
t1 = GetTickCount();
r2 = fib_jit (n);
t2 = GetTickCount();
}

else {
    fprintf (stderr, "%s: Wrong number of arguments\n", argv[0]);
	exit (-1);
}

printf ("  fib_c(%d) result: %d\n\texecution time: %lf\n", n, r1, (t1-t0) / 1000.0);
printf ("fib_jit(%d) result: %d\n\texecution time: %lf\n", n, r2, (t2-t1) / 1000.0);

return 0;
}