| #include <linux/linkage.h> |
| |
| /* |
| * Unsigned modulo operation for 32 bit integers. |
| * Input : op1 in Reg r5 |
| * op2 in Reg r6 |
| * Output: op1 mod op2 in Reg r3 |
| */ |
| |
| .text |
| .globl __umodsi3 |
| .type __umodsi3, @function |
| .ent __umodsi3 |
| |
| __umodsi3: |
| .frame r1, 0, r15 |
| |
| addik r1, r1, -12 |
| swi r29, r1, 0 |
| swi r30, r1, 4 |
| swi r31, r1, 8 |
| |
| beqi r6, div_by_zero /* div_by_zero - division error */ |
| beqid r5, result_is_zero /* result is zero */ |
| addik r3, r0, 0 /* clear div */ |
| addik r30, r0, 0 /* clear mod */ |
| addik r29, r0, 32 /* initialize the loop count */ |
| |
| /* check if r6 and r5 are equal /* if yes, return 0 */ |
| rsub r18, r5, r6 |
| beqi r18, return_here |
| |
| /* check if (uns)r6 is greater than (uns)r5. in that case, just return r5 */ |
| xor r18, r5, r6 |
| bgeid r18, 16 |
| addik r3, r5, 0 |
| blti r6, return_here |
| bri $lcheckr6 |
| rsub r18, r5, r6 /* microblazecmp */ |
| bgti r18, return_here |
| |
| /* if r6 [bit 31] is set, then return result as r5-r6 */ |
| $lcheckr6: |
| bgtid r6, div0 |
| addik r3, r0, 0 |
| addik r18, r0, 0x7fffffff |
| and r5, r5, r18 |
| and r6, r6, r18 |
| brid return_here |
| rsub r3, r6, r5 |
| /* first part: try to find the first '1' in the r5 */ |
| div0: |
| blti r5, div2 |
| 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 (r3 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: |
| bri return_here |
| div_by_zero: |
| result_is_zero: |
| or r3, r0, r0 /* set result to 0 */ |
| return_here: |
| /* restore values of csrs and that of r3 and the divisor and the dividend */ |
| lwi r29, r1, 0 |
| lwi r30, r1, 4 |
| lwi r31, r1, 8 |
| rtsd r15, 8 |
| addik r1, r1, 12 |
| |
| .size __umodsi3, . - __umodsi3 |
| .end __umodsi3 |
