mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-05 02:51:00 +00:00
77 lines
2.2 KiB
ArmAsm
77 lines
2.2 KiB
ArmAsm
/* # 1 "libgcc1.S" */
|
|
@ libgcc1 routines for ARM cpu.
|
|
@ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk)
|
|
dividend .req r0
|
|
divisor .req r1
|
|
result .req r2
|
|
curbit .req r3
|
|
/* ip .req r12 */
|
|
/* sp .req r13 */
|
|
/* lr .req r14 */
|
|
/* pc .req r15 */
|
|
.text
|
|
.globl __udivsi3
|
|
.type __udivsi3 ,function
|
|
.align 0
|
|
__udivsi3 :
|
|
cmp divisor, #0
|
|
beq Ldiv0
|
|
mov curbit, #1
|
|
mov result, #0
|
|
cmp dividend, divisor
|
|
bcc Lgot_result
|
|
Loop1:
|
|
@ Unless the divisor is very big, shift it up in multiples of
|
|
@ four bits, since this is the amount of unwinding in the main
|
|
@ division loop. Continue shifting until the divisor is
|
|
@ larger than the dividend.
|
|
cmp divisor, #0x10000000
|
|
cmpcc divisor, dividend
|
|
movcc divisor, divisor, lsl #4
|
|
movcc curbit, curbit, lsl #4
|
|
bcc Loop1
|
|
Lbignum:
|
|
@ For very big divisors, we must shift it a bit at a time, or
|
|
@ we will be in danger of overflowing.
|
|
cmp divisor, #0x80000000
|
|
cmpcc divisor, dividend
|
|
movcc divisor, divisor, lsl #1
|
|
movcc curbit, curbit, lsl #1
|
|
bcc Lbignum
|
|
Loop3:
|
|
@ Test for possible subtractions, and note which bits
|
|
@ are done in the result. On the final pass, this may subtract
|
|
@ too much from the dividend, but the result will be ok, since the
|
|
@ "bit" will have been shifted out at the bottom.
|
|
cmp dividend, divisor
|
|
subcs dividend, dividend, divisor
|
|
orrcs result, result, curbit
|
|
cmp dividend, divisor, lsr #1
|
|
subcs dividend, dividend, divisor, lsr #1
|
|
orrcs result, result, curbit, lsr #1
|
|
cmp dividend, divisor, lsr #2
|
|
subcs dividend, dividend, divisor, lsr #2
|
|
orrcs result, result, curbit, lsr #2
|
|
cmp dividend, divisor, lsr #3
|
|
subcs dividend, dividend, divisor, lsr #3
|
|
orrcs result, result, curbit, lsr #3
|
|
cmp dividend, #0 @ Early termination?
|
|
movnes curbit, curbit, lsr #4 @ No, any more bits to do?
|
|
movne divisor, divisor, lsr #4
|
|
bne Loop3
|
|
Lgot_result:
|
|
mov r0, result
|
|
mov pc, lr
|
|
Ldiv0:
|
|
str lr, [sp, #-4]!
|
|
bl __div0 (PLT)
|
|
mov r0, #0 @ about as wrong as it could be
|
|
ldmia sp!, {pc}
|
|
.size __udivsi3 , . - __udivsi3
|
|
/* # 235 "libgcc1.S" */
|
|
/* # 320 "libgcc1.S" */
|
|
/* # 421 "libgcc1.S" */
|
|
/* # 433 "libgcc1.S" */
|
|
/* # 456 "libgcc1.S" */
|
|
/* # 500 "libgcc1.S" */
|
|
/* # 580 "libgcc1.S" */
|