diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/ppc/lib/div64.S |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'arch/ppc/lib/div64.S')
-rw-r--r-- | arch/ppc/lib/div64.S | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/ppc/lib/div64.S b/arch/ppc/lib/div64.S new file mode 100644 index 000000000000..3527569e9926 --- /dev/null +++ b/arch/ppc/lib/div64.S | |||
@@ -0,0 +1,58 @@ | |||
1 | /* | ||
2 | * Divide a 64-bit unsigned number by a 32-bit unsigned number. | ||
3 | * This routine assumes that the top 32 bits of the dividend are | ||
4 | * non-zero to start with. | ||
5 | * On entry, r3 points to the dividend, which get overwritten with | ||
6 | * the 64-bit quotient, and r4 contains the divisor. | ||
7 | * On exit, r3 contains the remainder. | ||
8 | * | ||
9 | * Copyright (C) 2002 Paul Mackerras, IBM Corp. | ||
10 | * | ||
11 | * This program is free software; you can redistribute it and/or | ||
12 | * modify it under the terms of the GNU General Public License | ||
13 | * as published by the Free Software Foundation; either version | ||
14 | * 2 of the License, or (at your option) any later version. | ||
15 | */ | ||
16 | #include <asm/ppc_asm.h> | ||
17 | #include <asm/processor.h> | ||
18 | |||
19 | _GLOBAL(__div64_32) | ||
20 | lwz r5,0(r3) # get the dividend into r5/r6 | ||
21 | lwz r6,4(r3) | ||
22 | cmplw r5,r4 | ||
23 | li r7,0 | ||
24 | li r8,0 | ||
25 | blt 1f | ||
26 | divwu r7,r5,r4 # if dividend.hi >= divisor, | ||
27 | mullw r0,r7,r4 # quotient.hi = dividend.hi / divisor | ||
28 | subf. r5,r0,r5 # dividend.hi %= divisor | ||
29 | beq 3f | ||
30 | 1: mr r11,r5 # here dividend.hi != 0 | ||
31 | andis. r0,r5,0xc000 | ||
32 | bne 2f | ||
33 | cntlzw r0,r5 # we are shifting the dividend right | ||
34 | li r10,-1 # to make it < 2^32, and shifting | ||
35 | srw r10,r10,r0 # the divisor right the same amount, | ||
36 | add r9,r4,r10 # rounding up (so the estimate cannot | ||
37 | andc r11,r6,r10 # ever be too large, only too small) | ||
38 | andc r9,r9,r10 | ||
39 | or r11,r5,r11 | ||
40 | rotlw r9,r9,r0 | ||
41 | rotlw r11,r11,r0 | ||
42 | divwu r11,r11,r9 # then we divide the shifted quantities | ||
43 | 2: mullw r10,r11,r4 # to get an estimate of the quotient, | ||
44 | mulhwu r9,r11,r4 # multiply the estimate by the divisor, | ||
45 | subfc r6,r10,r6 # take the product from the divisor, | ||
46 | add r8,r8,r11 # and add the estimate to the accumulated | ||
47 | subfe. r5,r9,r5 # quotient | ||
48 | bne 1b | ||
49 | 3: cmplw r6,r4 | ||
50 | blt 4f | ||
51 | divwu r0,r6,r4 # perform the remaining 32-bit division | ||
52 | mullw r10,r0,r4 # and get the remainder | ||
53 | add r8,r8,r0 | ||
54 | subf r6,r10,r6 | ||
55 | 4: stw r7,0(r3) # return the quotient in *r3 | ||
56 | stw r8,4(r3) | ||
57 | mr r3,r6 # return the remainder in r3 | ||
58 | blr | ||