2 .macro ARM_DIV_BODY dividend, divisor, result, curbit
4 #if __LINUX_ARM_ARCH__ >= 5
8 sub \result, \curbit, \result
10 mov \divisor, \divisor, lsl \result
11 mov \curbit, \curbit, lsl \result
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
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.
29 1: cmp \divisor, #0x10000000
30 cmplo \divisor, \dividend
31 movlo \divisor, \divisor, lsl #4
32 movlo \curbit, \curbit, lsl #4
35 @ For very big divisors, we must shift it a bit at a time, or
36 @ we will be in danger of overflowing.
37 1: cmp \divisor, #0x80000000
38 cmplo \divisor, \dividend
39 movlo \divisor, \divisor, lsl #1
40 movlo \curbit, \curbit, lsl #1
48 1: 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
67 .macro ARM_DIV2_ORDER divisor, order
69 #if __LINUX_ARM_ARCH__ >= 5
72 rsb \order, \order, #31
76 cmp \divisor, #(1 << 16)
77 movhs \divisor, \divisor, lsr #16
81 cmp \divisor, #(1 << 8)
82 movhs \divisor, \divisor, lsr #8
83 addhs \order, \order, #8
85 cmp \divisor, #(1 << 4)
86 movhs \divisor, \divisor, lsr #4
87 addhs \order, \order, #4
89 cmp \divisor, #(1 << 2)
90 addhi \order, \order, #3
91 addls \order, \order, \divisor, lsr #1
101 eor ip, r0, r1 @ save the sign of the result.
103 rsbmi r1, r1, #0 @ loops below use unsigned.
104 subs r2, r1, #1 @ division by 1 or -1 ?
107 rsbmi r3, r0, #0 @ positive dividend value
110 tst r1, r2 @ divisor is power of 2 ?
113 ARM_DIV_BODY r3, r1, r0, r2
119 10: teq ip, r0 @ same sign ?
124 moveq r0, ip, asr #31
128 12: ARM_DIV2_ORDER r1, r2
139 mov r0, #0 @ About as wrong as it could be.