blob: 84e0bee6e8c716bc8c8222ca2b3bd8dda9f84146 [file] [log] [blame]
Michal Simek4e07dba2010-08-12 14:28:53 +02001#include <linux/linkage.h>
2
3/*
4* modulo operation for 32 bit integers.
5* Input : op1 in Reg r5
6* op2 in Reg r6
7* Output: op1 mod op2 in Reg r3
8*/
9
10 .text
11 .globl __modsi3
12 .type __modsi3, @function
13 .ent __modsi3
14
15__modsi3:
16 .frame r1, 0, r15
17
18 addik r1, r1, -16
19 swi r28, r1, 0
20 swi r29, r1, 4
21 swi r30, r1, 8
22 swi r31, r1, 12
23
24 beqi r6, div_by_zero /* div_by_zero division error */
25 beqi r5, result_is_zero /* result is zero */
26 bgeid r5, r5_pos
27 /* get the sign of the result [ depends only on the first arg] */
28 add r28, r5, r0
29 rsubi r5, r5, 0 /* make r5 positive */
30r5_pos:
31 bgei r6, r6_pos
32 rsubi r6, r6, 0 /* make r6 positive */
33r6_pos:
34 addik r3, r0, 0 /* clear mod */
35 addik r30, r0, 0 /* clear div */
36 addik r29, r0, 32 /* initialize the loop count */
37/* first part try to find the first '1' in the r5 */
38div1:
39 add r5, r5, r5 /* left shift logical r5 */
40 bgeid r5, div1
41 addik r29, r29, -1
42div2:
43 /* left shift logical r5 get the '1' into the carry */
44 add r5, r5, r5
45 addc r3, r3, r3 /* move that bit into the mod register */
46 rsub r31, r6, r3 /* try to subtract (r30 a r6) */
47 blti r31, mod_too_small
48 /* move the r31 to mod since the result was positive */
49 or r3, r0, r31
50 addik r30, r30, 1
51mod_too_small:
52 addik r29, r29, -1
53 beqi r29, loop_end
54 add r30, r30, r30 /* shift in the '1' into div */
55 bri div2 /* div2 */
56loop_end:
57 bgei r28, return_here
58 brid return_here
59 rsubi r3, r3, 0 /* negate the result */
60div_by_zero:
61result_is_zero:
62 or r3, r0, r0 /* set result to 0 [both mod as well as div are 0] */
63return_here:
64/* restore values of csrs and that of r3 and the divisor and the dividend */
65 lwi r28, r1, 0
66 lwi r29, r1, 4
67 lwi r30, r1, 8
68 lwi r31, r1, 12
69 rtsd r15, 8
70 addik r1, r1, 16
71
72.size __modsi3, . - __modsi3
73.end __modsi3