1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #include <linux/linkage.h> 3 4 /* 5 * Unsigned divide operation. 6 * Input : Divisor in Reg r5 7 * Dividend in Reg r6 8 * Output: Result in Reg r3 9 */ 10 11 .text 12 .globl __udivsi3 13 .type __udivsi3, @function 14 .ent __udivsi3 15 16 __udivsi3: 17 18 .frame r1, 0, r15 19 20 addik r1, r1, -12 21 swi r29, r1, 0 22 swi r30, r1, 4 23 swi r31, r1, 8 24 25 beqi r6, div_by_zero /* div_by_zero /* division error */ 26 beqid r5, result_is_zero /* result is zero */ 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 1 */ 31 rsub r18, r5, r6 32 beqid r18, return_here 33 addik r3, r0, 1 34 35 /* check if (uns)r6 is greater than (uns)r5. in that case, just return 0 */ 36 xor r18, r5, r6 37 bgeid r18, 16 38 add r3, r0, r0 /* we would anyways clear r3 */ 39 blti r6, return_here /* r6[bit 31 = 1] hence is greater */ 40 bri checkr6 41 rsub r18, r6, r5 /* microblazecmp */ 42 blti r18, return_here 43 44 /* if r6 [bit 31] is set, then return result as 1 */ 45 checkr6: 46 bgti r6, div0 47 brid return_here 48 addik r3, r0, 1 49 50 /* first part try to find the first '1' in the r5 */ 51 div0: 52 blti r5, div2 53 div1: 54 add r5, r5, r5 /* left shift logical r5 */ 55 bgtid r5, div1 56 addik r29, r29, -1 57 div2: 58 /* left shift logical r5 get the '1' into the carry */ 59 add r5, r5, r5 60 addc r30, r30, r30 /* move that bit into the mod register */ 61 rsub r31, r6, r30 /* try to subtract (r30 a r6) */ 62 blti r31, mod_too_small 63 /* move the r31 to mod since the result was positive */ 64 or r30, r0, r31 65 addik r3, r3, 1 66 mod_too_small: 67 addik r29, r29, -1 68 beqi r29, loop_end 69 add r3, r3, r3 /* shift in the '1' into div */ 70 bri div2 /* div2 */ 71 loop_end: 72 bri return_here 73 div_by_zero: 74 result_is_zero: 75 or r3, r0, r0 /* set result to 0 */ 76 return_here: 77 /* restore values of csrs and that of r3 and the divisor and the dividend */ 78 lwi r29, r1, 0 79 lwi r30, r1, 4 80 lwi r31, r1, 8 81 rtsd r15, 8 82 addik r1, r1, 12 83 84 .size __udivsi3, . - __udivsi3 85 .end __udivsi3 86