| Kyle Moffett | 78d58de | 2011-02-23 06:40:38 +0000 | [diff] [blame] | 1 | /* |
| 2 | * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux |
| 3 | * kernel sources (commit 85e2efbb1db9a18d218006706d6e4fbeb0216213, also |
| 4 | * known as 2.6.38-rc5). The source file copyrights are as follows: |
| 5 | * |
| 6 | * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org) |
| 7 | * |
| 8 | * Largely rewritten by Cort Dougan (cort@cs.nmt.edu) |
| 9 | * and Paul Mackerras. |
| 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 as |
| 13 | * published by the Free Software Foundation; either version 2 of |
| 14 | * the License, or (at your option) any later version. |
| 15 | */ |
| 16 | |
| 17 | #include <ppc_asm.tmpl> |
| 18 | #include <ppc_defs.h> |
| 19 | #include <config.h> |
| 20 | |
| 21 | /* |
| 22 | * Extended precision shifts. |
| 23 | * |
| 24 | * Updated to be valid for shift counts from 0 to 63 inclusive. |
| 25 | * -- Gabriel |
| 26 | * |
| 27 | * R3/R4 has 64 bit value |
| 28 | * R5 has shift count |
| 29 | * result in R3/R4 |
| 30 | * |
| 31 | * ashrdi3: arithmetic right shift (sign propagation) |
| 32 | * lshrdi3: logical right shift |
| 33 | * ashldi3: left shift |
| 34 | */ |
| 35 | .globl __ashrdi3 |
| 36 | __ashrdi3: |
| 37 | subfic r6,r5,32 |
| 38 | srw r4,r4,r5 # LSW = count > 31 ? 0 : LSW >> count |
| 39 | addi r7,r5,32 # could be xori, or addi with -32 |
| 40 | slw r6,r3,r6 # t1 = count > 31 ? 0 : MSW << (32-count) |
| 41 | rlwinm r8,r7,0,32 # t3 = (count < 32) ? 32 : 0 |
| 42 | sraw r7,r3,r7 # t2 = MSW >> (count-32) |
| 43 | or r4,r4,r6 # LSW |= t1 |
| 44 | slw r7,r7,r8 # t2 = (count < 32) ? 0 : t2 |
| 45 | sraw r3,r3,r5 # MSW = MSW >> count |
| 46 | or r4,r4,r7 # LSW |= t2 |
| 47 | blr |