xref: /netbsd-src/sys/external/bsd/sljit/dist/doc/tutorial/func_call.c (revision 99e10043c2d890154986b9f0cfb10c84949ba483)
1 #include "sljitLir.h"
2 
3 #include <stdio.h>
4 #include <stdlib.h>
5 
6 typedef long SLJIT_CALL (*func3_t)(long a, long b, long c);
7 
print_num(long a)8 static long SLJIT_CALL print_num(long a)
9 {
10 	printf("a = %ld\n", a);
11 	return a + 1;
12 }
13 
14 /*
15   This example, we generate a function like this:
16 
17 long func(long a, long b, long c)
18 {
19 	if ((a & 1) == 0)
20 		return print_num(c);
21 	return print_num(b);
22 }
23 */
24 
func_call(long a,long b,long c)25 static int func_call(long a, long b, long c)
26 {
27 	void *code;
28 	unsigned long len;
29 	func3_t func;
30 
31 	struct sljit_jump *out;
32 	struct sljit_jump *print_c;
33 
34 	/* Create a SLJIT compiler */
35 	struct sljit_compiler *C = sljit_create_compiler();
36 
37 	sljit_emit_enter(C, 0,  3,  1, 3, 0, 0, 0);
38 
39 	/*  a & 1 --> R0 */
40 	sljit_emit_op2(C, SLJIT_AND, SLJIT_R0, 0, SLJIT_S0, 0, SLJIT_IMM, 1);
41 	/* R0 == 0 --> jump print_c */
42 	print_c = sljit_emit_cmp(C, SLJIT_EQUAL, SLJIT_R0, 0, SLJIT_IMM, 0);
43 
44 	/* R0 = S1; print_num(R0) */
45 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_R0, 0, SLJIT_S1, 0);
46 	sljit_emit_ijump(C, SLJIT_CALL1, SLJIT_IMM, SLJIT_FUNC_OFFSET(print_num));
47 
48 	/* jump out */
49 	out = sljit_emit_jump(C, SLJIT_JUMP);
50 	/* print_c: */
51 	sljit_set_label(print_c, sljit_emit_label(C));
52 
53 	/* R0 = c; print_num(R0); */
54 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_R0, 0, SLJIT_S2, 0);
55 	sljit_emit_ijump(C, SLJIT_CALL1, SLJIT_IMM, SLJIT_FUNC_OFFSET(print_num));
56 
57 	/* out: */
58 	sljit_set_label(out, sljit_emit_label(C));
59 	sljit_emit_return(C, SLJIT_MOV, SLJIT_R0, 0);
60 
61 	/* Generate machine code */
62 	code = sljit_generate_code(C);
63 	len = sljit_get_generated_code_size(C);
64 
65 	/* Execute code */
66 	func = (func3_t)code;
67 	printf("func return %ld\n", func(a, b, c));
68 
69 	/* dump_code(code, len); */
70 
71 	/* Clean up */
72 	sljit_free_compiler(C);
73 	sljit_free_code(code);
74 	return 0;
75 }
76 
main()77 int main()
78 {
79 	return func_call(4, 5, 6);
80 }
81