umodsi3.S (2013B)
1/* SPDX-License-Identifier: GPL-2.0 */ 2#include <linux/linkage.h> 3 4/* 5 * Unsigned modulo operation for 32 bit integers. 6 * Input : op1 in Reg r5 7 * op2 in Reg r6 8 * Output: op1 mod op2 in Reg r3 9 */ 10 11 .text 12 .globl __umodsi3 13 .type __umodsi3, @function 14 .ent __umodsi3 15 16__umodsi3: 17 .frame r1, 0, r15 18 19 addik r1, r1, -12 20 swi r29, r1, 0 21 swi r30, r1, 4 22 swi r31, r1, 8 23 24 beqi r6, div_by_zero /* div_by_zero - division error */ 25 beqid r5, result_is_zero /* result is zero */ 26 addik r3, r0, 0 /* clear div */ 27 addik r30, r0, 0 /* clear mod */ 28 addik r29, r0, 32 /* initialize the loop count */ 29 30/* check if r6 and r5 are equal /* if yes, return 0 */ 31 rsub r18, r5, r6 32 beqi r18, return_here 33 34/* check if (uns)r6 is greater than (uns)r5. in that case, just return r5 */ 35 xor r18, r5, r6 36 bgeid r18, 16 37 addik r3, r5, 0 38 blti r6, return_here 39 bri $lcheckr6 40 rsub r18, r5, r6 /* microblazecmp */ 41 bgti r18, return_here 42 43/* if r6 [bit 31] is set, then return result as r5-r6 */ 44$lcheckr6: 45 bgtid r6, div0 46 addik r3, r0, 0 47 addik r18, r0, 0x7fffffff 48 and r5, r5, r18 49 and r6, r6, r18 50 brid return_here 51 rsub r3, r6, r5 52/* first part: try to find the first '1' in the r5 */ 53div0: 54 blti r5, div2 55div1: 56 add r5, r5, r5 /* left shift logical r5 */ 57 bgeid r5, div1 58 addik r29, r29, -1 59div2: 60 /* left shift logical r5 get the '1' into the carry */ 61 add r5, r5, r5 62 addc r3, r3, r3 /* move that bit into the mod register */ 63 rsub r31, r6, r3 /* try to subtract (r3 a r6) */ 64 blti r31, mod_too_small 65 /* move the r31 to mod since the result was positive */ 66 or r3, r0, r31 67 addik r30, r30, 1 68mod_too_small: 69 addik r29, r29, -1 70 beqi r29, loop_end 71 add r30, r30, r30 /* shift in the '1' into div */ 72 bri div2 /* div2 */ 73loop_end: 74 bri return_here 75div_by_zero: 76result_is_zero: 77 or r3, r0, r0 /* set result to 0 */ 78return_here: 79/* restore values of csrs and that of r3 and the divisor and the dividend */ 80 lwi r29, r1, 0 81 lwi r30, r1, 4 82 lwi r31, r1, 8 83 rtsd r15, 8 84 addik r1, r1, 12 85 86.size __umodsi3, . - __umodsi3 87.end __umodsi3