xref: /netbsd-src/sys/external/bsd/sljit/dist/doc/tutorial/func_call.c (revision 99e10043c2d890154986b9f0cfb10c84949ba483)
1*99e10043Salnsn #include "sljitLir.h"
2*99e10043Salnsn 
3*99e10043Salnsn #include <stdio.h>
4*99e10043Salnsn #include <stdlib.h>
5*99e10043Salnsn 
6*99e10043Salnsn typedef long SLJIT_CALL (*func3_t)(long a, long b, long c);
7*99e10043Salnsn 
print_num(long a)8*99e10043Salnsn static long SLJIT_CALL print_num(long a)
9*99e10043Salnsn {
10*99e10043Salnsn 	printf("a = %ld\n", a);
11*99e10043Salnsn 	return a + 1;
12*99e10043Salnsn }
13*99e10043Salnsn 
14*99e10043Salnsn /*
15*99e10043Salnsn   This example, we generate a function like this:
16*99e10043Salnsn 
17*99e10043Salnsn long func(long a, long b, long c)
18*99e10043Salnsn {
19*99e10043Salnsn 	if ((a & 1) == 0)
20*99e10043Salnsn 		return print_num(c);
21*99e10043Salnsn 	return print_num(b);
22*99e10043Salnsn }
23*99e10043Salnsn */
24*99e10043Salnsn 
func_call(long a,long b,long c)25*99e10043Salnsn static int func_call(long a, long b, long c)
26*99e10043Salnsn {
27*99e10043Salnsn 	void *code;
28*99e10043Salnsn 	unsigned long len;
29*99e10043Salnsn 	func3_t func;
30*99e10043Salnsn 
31*99e10043Salnsn 	struct sljit_jump *out;
32*99e10043Salnsn 	struct sljit_jump *print_c;
33*99e10043Salnsn 
34*99e10043Salnsn 	/* Create a SLJIT compiler */
35*99e10043Salnsn 	struct sljit_compiler *C = sljit_create_compiler();
36*99e10043Salnsn 
37*99e10043Salnsn 	sljit_emit_enter(C, 0,  3,  1, 3, 0, 0, 0);
38*99e10043Salnsn 
39*99e10043Salnsn 	/*  a & 1 --> R0 */
40*99e10043Salnsn 	sljit_emit_op2(C, SLJIT_AND, SLJIT_R0, 0, SLJIT_S0, 0, SLJIT_IMM, 1);
41*99e10043Salnsn 	/* R0 == 0 --> jump print_c */
42*99e10043Salnsn 	print_c = sljit_emit_cmp(C, SLJIT_EQUAL, SLJIT_R0, 0, SLJIT_IMM, 0);
43*99e10043Salnsn 
44*99e10043Salnsn 	/* R0 = S1; print_num(R0) */
45*99e10043Salnsn 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_R0, 0, SLJIT_S1, 0);
46*99e10043Salnsn 	sljit_emit_ijump(C, SLJIT_CALL1, SLJIT_IMM, SLJIT_FUNC_OFFSET(print_num));
47*99e10043Salnsn 
48*99e10043Salnsn 	/* jump out */
49*99e10043Salnsn 	out = sljit_emit_jump(C, SLJIT_JUMP);
50*99e10043Salnsn 	/* print_c: */
51*99e10043Salnsn 	sljit_set_label(print_c, sljit_emit_label(C));
52*99e10043Salnsn 
53*99e10043Salnsn 	/* R0 = c; print_num(R0); */
54*99e10043Salnsn 	sljit_emit_op1(C, SLJIT_MOV, SLJIT_R0, 0, SLJIT_S2, 0);
55*99e10043Salnsn 	sljit_emit_ijump(C, SLJIT_CALL1, SLJIT_IMM, SLJIT_FUNC_OFFSET(print_num));
56*99e10043Salnsn 
57*99e10043Salnsn 	/* out: */
58*99e10043Salnsn 	sljit_set_label(out, sljit_emit_label(C));
59*99e10043Salnsn 	sljit_emit_return(C, SLJIT_MOV, SLJIT_R0, 0);
60*99e10043Salnsn 
61*99e10043Salnsn 	/* Generate machine code */
62*99e10043Salnsn 	code = sljit_generate_code(C);
63*99e10043Salnsn 	len = sljit_get_generated_code_size(C);
64*99e10043Salnsn 
65*99e10043Salnsn 	/* Execute code */
66*99e10043Salnsn 	func = (func3_t)code;
67*99e10043Salnsn 	printf("func return %ld\n", func(a, b, c));
68*99e10043Salnsn 
69*99e10043Salnsn 	/* dump_code(code, len); */
70*99e10043Salnsn 
71*99e10043Salnsn 	/* Clean up */
72*99e10043Salnsn 	sljit_free_compiler(C);
73*99e10043Salnsn 	sljit_free_code(code);
74*99e10043Salnsn 	return 0;
75*99e10043Salnsn }
76*99e10043Salnsn 
main()77*99e10043Salnsn int main()
78*99e10043Salnsn {
79*99e10043Salnsn 	return func_call(4, 5, 6);
80*99e10043Salnsn }
81