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path: root/arch/microblaze/lib/modsi3.S
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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 ``` ``````#include /* * 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 ``````