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git01.mediatek.com / filogic / uboot / f2d6076dd377ec5a8a079ca6762a1a9afbeeeed9 / . / arch / arm / lib / _divsi3.S
blob: cfbadb2ab99f094d88bb81b4a4194187d660b195 [file] [log] [blame]
Wolfgang Denk4646d2a2006-05-30 15:56:48 +0200[diff] [blame]1
2.macro ARM_DIV_BODY dividend, divisor, result, curbit
3
4#if __LINUX_ARM_ARCH__ >= 5
5
6 clz \curbit, \divisor
7 clz \result, \dividend
8 sub \result, \curbit, \result
9 mov \curbit, #1
10 mov \divisor, \divisor, lsl \result
11 mov \curbit, \curbit, lsl \result
12 mov \result, #0
13
14#else
15
16 @ Initially shift the divisor left 3 bits if possible,
17 @ set curbit accordingly. This allows for curbit to be located
18 @ at the left end of each 4 bit nibbles in the division loop
19 @ to save one loop in most cases.
20 tst \divisor, #0xe0000000
21 moveq \divisor, \divisor, lsl #3
22 moveq \curbit, #8
23 movne \curbit, #1
24
25 @ Unless the divisor is very big, shift it up in multiples of
26 @ four bits, since this is the amount of unwinding in the main
27 @ division loop. Continue shifting until the divisor is
28 @ larger than the dividend.
291: cmp \divisor, #0x10000000
30 cmplo \divisor, \dividend
31 movlo \divisor, \divisor, lsl #4
32 movlo \curbit, \curbit, lsl #4
33 blo 1b
34
35 @ For very big divisors, we must shift it a bit at a time, or
36 @ we will be in danger of overflowing.
371: cmp \divisor, #0x80000000
38 cmplo \divisor, \dividend
39 movlo \divisor, \divisor, lsl #1
40 movlo \curbit, \curbit, lsl #1
41 blo 1b
42
43 mov \result, #0
44
45#endif
46
47 @ Division loop
481: cmp \dividend, \divisor
49 subhs \dividend, \dividend, \divisor
50 orrhs \result, \result, \curbit
51 cmp \dividend, \divisor, lsr #1
52 subhs \dividend, \dividend, \divisor, lsr #1
53 orrhs \result, \result, \curbit, lsr #1
54 cmp \dividend, \divisor, lsr #2
55 subhs \dividend, \dividend, \divisor, lsr #2
56 orrhs \result, \result, \curbit, lsr #2
57 cmp \dividend, \divisor, lsr #3
58 subhs \dividend, \dividend, \divisor, lsr #3
59 orrhs \result, \result, \curbit, lsr #3
60 cmp \dividend, #0 @ Early termination?
61 movnes \curbit, \curbit, lsr #4 @ No, any more bits to do?
62 movne \divisor, \divisor, lsr #4
63 bne 1b
64
65.endm
66
67.macro ARM_DIV2_ORDER divisor, order
68
69#if __LINUX_ARM_ARCH__ >= 5
70
71 clz \order, \divisor
72 rsb \order, \order, #31
73
74#else
75
76 cmp \divisor, #(1 << 16)
77 movhs \divisor, \divisor, lsr #16
78 movhs \order, #16
79 movlo \order, #0
80
81 cmp \divisor, #(1 << 8)
82 movhs \divisor, \divisor, lsr #8
83 addhs \order, \order, #8
84
85 cmp \divisor, #(1 << 4)
86 movhs \divisor, \divisor, lsr #4
87 addhs \order, \order, #4
88
89 cmp \divisor, #(1 << 2)
90 addhi \order, \order, #3
91 addls \order, \order, \divisor, lsr #1
92
93#endif
94
95.endm
96
97 .align 5
98.globl __divsi3
Wolfgang Denk8a5ddb12009-08-06 21:29:59 +0200[diff] [blame]99.globl __aeabi_idiv
Wolfgang Denk4646d2a2006-05-30 15:56:48 +0200[diff] [blame]100__divsi3:
Wolfgang Denk8a5ddb12009-08-06 21:29:59 +0200[diff] [blame]101__aeabi_idiv:
Wolfgang Denk4646d2a2006-05-30 15:56:48 +0200[diff] [blame]102 cmp r1, #0
103 eor ip, r0, r1 @ save the sign of the result.
104 beq Ldiv0
105 rsbmi r1, r1, #0 @ loops below use unsigned.
106 subs r2, r1, #1 @ division by 1 or -1 ?
107 beq 10f
108 movs r3, r0
109 rsbmi r3, r0, #0 @ positive dividend value
110 cmp r3, r1
111 bls 11f
112 tst r1, r2 @ divisor is power of 2 ?
113 beq 12f
114
115 ARM_DIV_BODY r3, r1, r0, r2
116
117 cmp ip, #0
118 rsbmi r0, r0, #0
119 mov pc, lr
120
12110: teq ip, r0 @ same sign ?
122 rsbmi r0, r0, #0
123 mov pc, lr
124
12511: movlo r0, #0
126 moveq r0, ip, asr #31
127 orreq r0, r0, #1
128 mov pc, lr
129
13012: ARM_DIV2_ORDER r1, r2
131
132 cmp ip, #0
133 mov r0, r3, lsr r2
134 rsbmi r0, r0, #0
135 mov pc, lr
136
137Ldiv0:
138
139 str lr, [sp, #-4]!
140 bl __div0
141 mov r0, #0 @ About as wrong as it could be.
142 ldr pc, [sp], #4