xref: /netbsd-src/sys/external/bsd/sljit/dist/doc/tutorial/array_access.c (revision 99e10043c2d890154986b9f0cfb10c84949ba483)
1 #include "sljitLir.h"
2 
3 #include <stdio.h>
4 #include <stdlib.h>
5 
6 typedef long SLJIT_CALL (*func_arr_t)(long *arr, long narr);
7 
print_num(long a)8 static long SLJIT_CALL print_num(long a)
9 {
10 	printf("num = %ld\n", a);
11 	return a + 1;
12 }
13 
14 /*
15   This example, we generate a function like this:
16 
17 long func(long *array, long narray)
18 {
19 	long i;
20 	for (i = 0; i < narray; ++i)
21 		print_num(array[i]);
22 	return narray;
23 }
24 
25 */
26 
array_access(long * arr,long narr)27 static int array_access(long *arr, long narr)
28 {
29 	void *code;
30 	unsigned long len;
31 	func_arr_t func;
32 
33 	/* Create a SLJIT compiler */
34 	struct sljit_compiler *C = sljit_create_compiler();
35 
36 	sljit_emit_enter(C, 0,  2,  1, 3, 0, 0, 0);
37 	/*                  opt arg R  S  FR FS local_size */
38 	sljit_emit_op2(C, SLJIT_XOR, SLJIT_S2, 0, SLJIT_S2, 0, SLJIT_S2, 0);				// S2 = 0
39 	struct sljit_label *loopstart = sljit_emit_label(C);								// loopstart:
40 	struct sljit_jump *out = sljit_emit_cmp(C, SLJIT_GREATER_EQUAL, SLJIT_S2, 0, SLJIT_S1, 0);	// S2 >= a --> jump out
41 
42 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_R0, 0, SLJIT_MEM2(SLJIT_S0, SLJIT_S2), SLJIT_WORD_SHIFT);// R0 = (long *)S0[S2];
43 	sljit_emit_ijump(C, SLJIT_CALL1, SLJIT_IMM, SLJIT_FUNC_OFFSET(print_num));					// print_num(R0);
44 
45 	sljit_emit_op2(C, SLJIT_ADD, SLJIT_S2, 0, SLJIT_S2, 0, SLJIT_IMM, 1);						// S2 += 1
46 	sljit_set_label(sljit_emit_jump(C, SLJIT_JUMP), loopstart);									// jump loopstart
47 	sljit_set_label(out, sljit_emit_label(C));											// out:
48 	sljit_emit_return(C, SLJIT_MOV, SLJIT_S1, 0);										// return RET
49 
50 	/* Generate machine code */
51 	code = sljit_generate_code(C);
52 	len = sljit_get_generated_code_size(C);
53 
54 	/* Execute code */
55 	func = (func_arr_t)code;
56 	printf("func return %ld\n", func(arr, narr));
57 
58 	/* dump_code(code, len); */
59 
60 	/* Clean up */
61 	sljit_free_compiler(C);
62 	sljit_free_code(code);
63 	return 0;
64 }
65 
main()66 int main()
67 {
68 	long arr[8] = { 3, -10, 4, 6, 8, 12, 2000 };
69 	return array_access(arr, 8);
70 }
71