add new dfboot loader - a complete revison of romboot code.
[openwrt/svn-archive/archive.git] / target / linux / at91-2.6 / image / dfboot / src / _udivsi3.S
1 /* # 1 "libgcc1.S" */
2 @ libgcc1 routines for ARM cpu.
3 @ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk)
4 dividend .req r0
5 divisor .req r1
6 result .req r2
7 curbit .req r3
8 /* ip .req r12 */
9 /* sp .req r13 */
10 /* lr .req r14 */
11 /* pc .req r15 */
12 .text
13 .globl __udivsi3
14 .type __udivsi3 ,function
15 .align 0
16 __udivsi3 :
17 cmp divisor, #0
18 beq Ldiv0
19 mov curbit, #1
20 mov result, #0
21 cmp dividend, divisor
22 bcc Lgot_result
23 Loop1:
24 @ Unless the divisor is very big, shift it up in multiples of
25 @ four bits, since this is the amount of unwinding in the main
26 @ division loop. Continue shifting until the divisor is
27 @ larger than the dividend.
28 cmp divisor, #0x10000000
29 cmpcc divisor, dividend
30 movcc divisor, divisor, lsl #4
31 movcc curbit, curbit, lsl #4
32 bcc Loop1
33 Lbignum:
34 @ For very big divisors, we must shift it a bit at a time, or
35 @ we will be in danger of overflowing.
36 cmp divisor, #0x80000000
37 cmpcc divisor, dividend
38 movcc divisor, divisor, lsl #1
39 movcc curbit, curbit, lsl #1
40 bcc Lbignum
41 Loop3:
42 @ Test for possible subtractions, and note which bits
43 @ are done in the result. On the final pass, this may subtract
44 @ too much from the dividend, but the result will be ok, since the
45 @ "bit" will have been shifted out at the bottom.
46 cmp dividend, divisor
47 subcs dividend, dividend, divisor
48 orrcs result, result, curbit
49 cmp dividend, divisor, lsr #1
50 subcs dividend, dividend, divisor, lsr #1
51 orrcs result, result, curbit, lsr #1
52 cmp dividend, divisor, lsr #2
53 subcs dividend, dividend, divisor, lsr #2
54 orrcs result, result, curbit, lsr #2
55 cmp dividend, divisor, lsr #3
56 subcs dividend, dividend, divisor, lsr #3
57 orrcs result, result, curbit, lsr #3
58 cmp dividend, #0 @ Early termination?
59 movnes curbit, curbit, lsr #4 @ No, any more bits to do?
60 movne divisor, divisor, lsr #4
61 bne Loop3
62 Lgot_result:
63 mov r0, result
64 mov pc, lr
65 Ldiv0:
66 str lr, [sp, #-4]!
67 bl __div0 (PLT)
68 mov r0, #0 @ about as wrong as it could be
69 ldmia sp!, {pc}
70 .size __udivsi3 , . - __udivsi3
71 /* # 235 "libgcc1.S" */
72 /* # 320 "libgcc1.S" */
73 /* # 421 "libgcc1.S" */
74 /* # 433 "libgcc1.S" */
75 /* # 456 "libgcc1.S" */
76 /* # 500 "libgcc1.S" */
77 /* # 580 "libgcc1.S" */