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c609719b WD |
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 | |
ac6dbb85 WD |
9 | /* ip .req r12 */ |
10 | /* sp .req r13 */ | |
11 | /* lr .req r14 */ | |
12 | /* pc .req r15 */ | |
c609719b WD |
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" */ |