add new dfboot loader - a complete revison of romboot code.
[openwrt/svn-archive/archive.git] / target / linux / at91-2.6 / image / dfboot / src / _umodsi3.S
1 /* # 1 "libgcc1.S" */
2 @ libgcc1 routines for ARM cpu.
3 @ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk)
4 /* # 145 "libgcc1.S" */
5 dividend .req r0
6 divisor .req r1
7 overdone .req r2
8 curbit .req r3
9 /* ip .req r12 */
10 /* sp .req r13 */
11 /* lr .req r14 */
12 /* pc .req r15 */
13 .text
14 .globl __umodsi3
15 .type __umodsi3 ,function
16 .align 0
17 __umodsi3 :
18 cmp divisor, #0
19 beq Ldiv0
20 mov curbit, #1
21 cmp dividend, divisor
22 movcc pc, lr
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. On the final pass, this may
43 @ subtract too much from the dividend, so keep track of which
44 @ subtractions are done, we can fix them up afterwards...
45 mov overdone, #0
46 cmp dividend, divisor
47 subcs dividend, dividend, divisor
48 cmp dividend, divisor, lsr #1
49 subcs dividend, dividend, divisor, lsr #1
50 orrcs overdone, overdone, curbit, ror #1
51 cmp dividend, divisor, lsr #2
52 subcs dividend, dividend, divisor, lsr #2
53 orrcs overdone, overdone, curbit, ror #2
54 cmp dividend, divisor, lsr #3
55 subcs dividend, dividend, divisor, lsr #3
56 orrcs overdone, overdone, curbit, ror #3
57 mov ip, curbit
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 @ Any subtractions that we should not have done will be recorded in
63 @ the top three bits of "overdone". Exactly which were not needed
64 @ are governed by the position of the bit, stored in ip.
65 @ If we terminated early, because dividend became zero,
66 @ then none of the below will match, since the bit in ip will not be
67 @ in the bottom nibble.
68 ands overdone, overdone, #0xe0000000
69 moveq pc, lr @ No fixups needed
70 tst overdone, ip, ror #3
71 addne dividend, dividend, divisor, lsr #3
72 tst overdone, ip, ror #2
73 addne dividend, dividend, divisor, lsr #2
74 tst overdone, ip, ror #1
75 addne dividend, dividend, divisor, lsr #1
76 mov pc, lr
77 Ldiv0:
78 str lr, [sp, #-4]!
79 bl __div0 (PLT)
80 mov r0, #0 @ about as wrong as it could be
81 ldmia sp!, {pc}
82 .size __umodsi3 , . - __umodsi3
83 /* # 320 "libgcc1.S" */
84 /* # 421 "libgcc1.S" */
85 /* # 433 "libgcc1.S" */
86 /* # 456 "libgcc1.S" */
87 /* # 500 "libgcc1.S" */
88 /* # 580 "libgcc1.S" */