1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #include <linux/linkage.h> 3 4 /* 5 * Divide operation for 32 bit integers. 6 * Input : Dividend in Reg r5 7 * Divisor in Reg r6 8 * Output: Result in Reg r3 9 */ 10 .text 11 .globl __divsi3 12 .type __divsi3, @function 13 .ent __divsi3 14 __divsi3: 15 .frame r1, 0, r15 16 17 addik r1, r1, -16 18 swi r28, r1, 0 19 swi r29, r1, 4 20 swi r30, r1, 8 21 swi r31, r1, 12 22 23 beqi r6, div_by_zero /* div_by_zero - division error */ 24 beqi r5, result_is_zero /* result is zero */ 25 bgeid r5, r5_pos 26 xor r28, r5, r6 /* get the sign of the result */ 27 rsubi r5, r5, 0 /* make r5 positive */ 28 r5_pos: 29 bgei r6, r6_pos 30 rsubi r6, r6, 0 /* make r6 positive */ 31 r6_pos: 32 addik r30, r0, 0 /* clear mod */ 33 addik r3, r0, 0 /* clear div */ 34 addik r29, r0, 32 /* initialize the loop count */ 35 36 /* first part try to find the first '1' in the r5 */ 37 div0: 38 blti r5, div2 /* this traps r5 == 0x80000000 */ 39 div1: 40 add r5, r5, r5 /* left shift logical r5 */ 41 bgtid r5, div1 42 addik r29, r29, -1 43 div2: 44 /* left shift logical r5 get the '1' into the carry */ 45 add r5, r5, r5 46 addc r30, r30, r30 /* move that bit into the mod register */ 47 rsub r31, r6, r30 /* try to subtract (r30 a r6) */ 48 blti r31, mod_too_small 49 /* move the r31 to mod since the result was positive */ 50 or r30, r0, r31 51 addik r3, r3, 1 52 mod_too_small: 53 addik r29, r29, -1 54 beqi r29, loop_end 55 add r3, r3, r3 /* shift in the '1' into div */ 56 bri div2 /* div2 */ 57 loop_end: 58 bgei r28, return_here 59 brid return_here 60 rsubi r3, r3, 0 /* negate the result */ 61 div_by_zero: 62 result_is_zero: 63 or r3, r0, r0 /* set result to 0 */ 64 return_here: 65 /* restore values of csrs and that of r3 and the divisor and the dividend */ 66 lwi r28, r1, 0 67 lwi r29, r1, 4 68 lwi r30, r1, 8 69 lwi r31, r1, 12 70 rtsd r15, 8 71 addik r1, r1, 16 72 73 .size __divsi3, . - __divsi3 74 .end __divsi3 75