6b13f685e
 김민수
BSP 최초 추가
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#include <linux/linkage.h>
/*
* Unsigned divide operation.
* Input : Divisor in Reg r5
* Dividend in Reg r6
* Output: Result in Reg r3
*/
.text
.globl __udivsi3
.type __udivsi3, @function
.ent __udivsi3
__udivsi3:
.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 r30, r0, 0 /* clear mod */
addik r29, r0, 32 /* initialize the loop count */
/* check if r6 and r5 are equal - if yes, return 1 */
rsub r18, r5, r6
beqid r18, return_here
addik r3, r0, 1
/* check if (uns)r6 is greater than (uns)r5. in that case, just return 0 */
xor r18, r5, r6
bgeid r18, 16
add r3, r0, r0 /* we would anyways clear r3 */
blti r6, return_here /* r6[bit 31 = 1] hence is greater */
bri checkr6
rsub r18, r6, r5 /* microblazecmp */
blti r18, return_here
/* if r6 [bit 31] is set, then return result as 1 */
checkr6:
bgti r6, div0
brid return_here
addik r3, r0, 1
/* first part try to find the first '1' in the r5 */
div0:
blti r5, div2
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:
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 __udivsi3, . - __udivsi3
.end __udivsi3
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