| #include <linux/linkage.h> |
| |
| /* |
| * modulo operation for 32 bit integers. |
| * Input : op1 in Reg r5 |
| * op2 in Reg r6 |
| * Output: op1 mod op2 in Reg r3 |
| */ |
| |
| .text |
| .globl __modsi3 |
| .type __modsi3, @function |
| .ent __modsi3 |
| |
| __modsi3: |
| .frame r1, 0, r15 |
| |
| addik r1, r1, -16 |
| swi r28, r1, 0 |
| swi r29, r1, 4 |
| swi r30, r1, 8 |
| swi r31, r1, 12 |
| |
| beqi r6, div_by_zero /* div_by_zero division error */ |
| beqi r5, result_is_zero /* result is zero */ |
| bgeid r5, r5_pos |
| /* get the sign of the result [ depends only on the first arg] */ |
| add r28, r5, r0 |
| rsubi r5, r5, 0 /* make r5 positive */ |
| r5_pos: |
| bgei r6, r6_pos |
| rsubi r6, r6, 0 /* make r6 positive */ |
| r6_pos: |
| addik r3, r0, 0 /* clear mod */ |
| addik r30, r0, 0 /* clear div */ |
| addik r29, r0, 32 /* initialize the loop count */ |
| /* first part try to find the first '1' in the r5 */ |
| div1: |
| add r5, r5, r5 /* left shift logical r5 */ |
| bgeid r5, div1 |
| addik r29, r29, -1 |
| div2: |
| /* left shift logical r5 get the '1' into the carry */ |
| add r5, r5, r5 |
| addc r3, r3, r3 /* move that bit into the mod register */ |
| rsub r31, r6, r3 /* try to subtract (r30 a r6) */ |
| blti r31, mod_too_small |
| /* move the r31 to mod since the result was positive */ |
| or r3, r0, r31 |
| addik r30, r30, 1 |
| mod_too_small: |
| addik r29, r29, -1 |
| beqi r29, loop_end |
| add r30, r30, r30 /* shift in the '1' into div */ |
| bri div2 /* div2 */ |
| loop_end: |
| bgei r28, return_here |
| brid return_here |
| rsubi r3, r3, 0 /* negate the result */ |
| div_by_zero: |
| result_is_zero: |
| or r3, r0, r0 /* set result to 0 [both mod as well as div are 0] */ |
| return_here: |
| /* restore values of csrs and that of r3 and the divisor and the dividend */ |
| lwi r28, r1, 0 |
| lwi r29, r1, 4 |
| lwi r30, r1, 8 |
| lwi r31, r1, 12 |
| rtsd r15, 8 |
| addik r1, r1, 16 |
| |
| .size __modsi3, . - __modsi3 |
| .end __modsi3 |
