1 #include <linux/linkage.h>
3 .macro ARM_MOD_BODY dividend, divisor, order, spare
5 #if __LINUX_ARM_ARCH__ >= 5
9 sub \order, \order, \spare
10 mov \divisor, \divisor, lsl \order
16 @ Unless the divisor is very big, shift it up in multiples of
17 @ four bits, since this is the amount of unwinding in the main
18 @ division loop. Continue shifting until the divisor is
19 @ larger than the dividend.
20 1: cmp \divisor, #0x10000000
21 cmplo \divisor, \dividend
22 movlo \divisor, \divisor, lsl #4
23 addlo \order, \order, #4
26 @ For very big divisors, we must shift it a bit at a time, or
27 @ we will be in danger of overflowing.
28 1: cmp \divisor, #0x80000000
29 cmplo \divisor, \dividend
30 movlo \divisor, \divisor, lsl #1
31 addlo \order, \order, #1
36 @ Perform all needed substractions to keep only the reminder.
37 @ Do comparisons in batch of 4 first.
38 subs \order, \order, #3 @ yes, 3 is intended here
41 1: cmp \dividend, \divisor
42 subhs \dividend, \dividend, \divisor
43 cmp \dividend, \divisor, lsr #1
44 subhs \dividend, \dividend, \divisor, lsr #1
45 cmp \dividend, \divisor, lsr #2
46 subhs \dividend, \dividend, \divisor, lsr #2
47 cmp \dividend, \divisor, lsr #3
48 subhs \dividend, \dividend, \divisor, lsr #3
50 mov \divisor, \divisor, lsr #4
51 subges \order, \order, #4
58 @ Either 1, 2 or 3 comparison/substractions are left.
62 cmp \dividend, \divisor
63 subhs \dividend, \dividend, \divisor
64 mov \divisor, \divisor, lsr #1
65 3: cmp \dividend, \divisor
66 subhs \dividend, \dividend, \divisor
67 mov \divisor, \divisor, lsr #1
68 4: cmp \dividend, \divisor
69 subhs \dividend, \dividend, \divisor
77 rsbmi r1, r1, #0 @ loops below use unsigned.
78 movs ip, r0 @ preserve sign of dividend
79 rsbmi r0, r0, #0 @ if negative make positive
80 subs r2, r1, #1 @ compare divisor with 1
81 cmpne r0, r1 @ compare dividend with divisor
83 tsthi r1, r2 @ see if divisor is power of 2
87 ARM_MOD_BODY r0, r1, r2, r3
98 mov r0, #0 @ About as wrong as it could be.