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