xref: /netbsd-src/sys/external/bsd/sljit/dist/doc/tutorial/temp_var.c (revision 99e10043c2d890154986b9f0cfb10c84949ba483)
1 #include "sljitLir.h"
2 
3 #include <stdio.h>
4 #include <stdlib.h>
5 
6 typedef long (*func3_t)(long a, long b, long c);
7 
print_arr(long * a,long n)8 static long SLJIT_CALL print_arr(long *a, long n)
9 {
10 	long i;
11 	long sum = 0;
12 	for (i = 0; i < n; ++i) {
13 		sum += a[i];
14 		printf("arr[%ld] = %ld\n", i, a[i]);
15 	}
16 	return sum;
17 }
18 
19 /*
20   This example, we generate a function like this:
21 
22 long func(long a, long b, long c)
23 {
24 	long arr[3] = { a, b, c };
25 	return print_arr(arr, 3);
26 }
27 */
28 
temp_var(long a,long b,long c)29 static int temp_var(long a, long b, long c)
30 {
31 	void *code;
32 	unsigned long len;
33 	func3_t func;
34 
35 	/* Create a SLJIT compiler */
36 	struct sljit_compiler *C = sljit_create_compiler();
37 
38 	/* reserved space in stack for long arr[3] */
39 	sljit_emit_enter(C, 0,  3,  2, 3, 0, 0, 3 * sizeof(long));
40 	/*                  opt arg R  S  FR FS local_size */
41 
42 	/* arr[0] = S0, SLJIT_SP is the init address of local var */
43 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_MEM1(SLJIT_SP), 0, SLJIT_S0, 0);
44 	/* arr[1] = S1 */
45 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_MEM1(SLJIT_SP), 1 * sizeof(long), SLJIT_S1, 0);
46 	/* arr[2] = S2 */
47 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_MEM1(SLJIT_SP), 2 * sizeof(long), SLJIT_S2, 0);
48 
49 	/* R0 = arr; in fact SLJIT_SP is the address of arr, but can't do so in SLJIT */
50 	sljit_get_local_base(C, SLJIT_R0, 0, 0);	/* get the address of local variables */
51 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_R1, 0, SLJIT_IMM, 3);	/* R1 = 3; */
52 	sljit_emit_ijump(C, SLJIT_CALL2, SLJIT_IMM, SLJIT_FUNC_OFFSET(print_arr));
53 	sljit_emit_return(C, SLJIT_MOV, SLJIT_R0, 0);
54 
55 	/* Generate machine code */
56 	code = sljit_generate_code(C);
57 	len = sljit_get_generated_code_size(C);
58 
59 	/* Execute code */
60 	func = (func3_t)code;
61 	printf("func return %ld\n", func(a, b, c));
62 
63 	/* dump_code(code, len); */
64 
65 	/* Clean up */
66 	sljit_free_compiler(C);
67 	sljit_free_code(code);
68 	return 0;
69 }
70 
main()71 int main()
72 {
73 	return temp_var(7, 8, 9);
74 }
75