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 #include /* * Divide operation for 32 bit integers. * Input : Dividend in Reg r5 * Divisor in Reg r6 * Output: Result in Reg r3 */ .text .globl __divsi3 .type __divsi3, @function .ent __divsi3 __divsi3: .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 xor r28, r5, r6 /* get the sign of the result */ rsubi r5, r5, 0 /* make r5 positive */ r5_pos: bgei r6, r6_pos rsubi r6, r6, 0 /* make r6 positive */ r6_pos: addik r30, r0, 0 /* clear mod */ addik r3, r0, 0 /* clear div */ addik r29, r0, 32 /* initialize the loop count */ /* first part try to find the first '1' in the r5 */ div0: blti r5, div2 /* this traps r5 == 0x80000000 */ div1: add r5, r5, r5 /* left shift logical r5 */ bgtid r5, div1 addik r29, r29, -1 div2: /* left shift logical r5 get the '1' into the carry */ add r5, r5, r5 addc r30, r30, r30 /* move that bit into the mod register */ rsub r31, r6, r30 /* try to subtract (r30 a r6) */ blti r31, mod_too_small /* move the r31 to mod since the result was positive */ or r30, r0, r31 addik r3, r3, 1 mod_too_small: addik r29, r29, -1 beqi r29, loop_end add r3, r3, r3 /* 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 */ 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 __divsi3, . - __divsi3 .end __divsi3