diff options
Diffstat (limited to 'arch/microblaze/lib/umodsi3.S')
| -rw-r--r-- | arch/microblaze/lib/umodsi3.S | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/arch/microblaze/lib/umodsi3.S b/arch/microblaze/lib/umodsi3.S new file mode 100644 index 0000000..17d16ba --- /dev/null +++ b/arch/microblaze/lib/umodsi3.S @@ -0,0 +1,86 @@ +#include <linux/linkage.h> + +/* + * Unsigned modulo operation for 32 bit integers. + * Input : op1 in Reg r5 + * op2 in Reg r6 + * Output: op1 mod op2 in Reg r3 + */ + + .text + .globl __umodsi3 + .type __umodsi3, @function + .ent __umodsi3 + +__umodsi3: + .frame r1, 0, r15 + + addik r1, r1, -12 + swi r29, r1, 0 + swi r30, r1, 4 + swi r31, r1, 8 + + beqi r6, div_by_zero /* div_by_zero - division error */ + beqid r5, result_is_zero /* result is zero */ + addik r3, r0, 0 /* clear div */ + addik r30, r0, 0 /* clear mod */ + addik r29, r0, 32 /* initialize the loop count */ + +/* check if r6 and r5 are equal /* if yes, return 0 */ + rsub r18, r5, r6 + beqi r18, return_here + +/* check if (uns)r6 is greater than (uns)r5. in that case, just return r5 */ + xor r18, r5, r6 + bgeid r18, 16 + addik r3, r5, 0 + blti r6, return_here + bri $lcheckr6 + rsub r18, r5, r6 /* microblazecmp */ + bgti r18, return_here + +/* if r6 [bit 31] is set, then return result as r5-r6 */ +$lcheckr6: + bgtid r6, div0 + addik r3, r0, 0 + addik r18, r0, 0x7fffffff + and r5, r5, r18 + and r6, r6, r18 + brid return_here + rsub r3, r6, r5 +/* first part: try to find the first '1' in the r5 */ +div0: + blti r5, div2 +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 (r3 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: + bri return_here +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 r29, r1, 0 + lwi r30, r1, 4 + lwi r31, r1, 8 + rtsd r15, 8 + addik r1, r1, 12 + +.size __umodsi3, . - __umodsi3 +.end __umodsi3 |
