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- #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
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