Mercurial > hg > CbC > CbC_gcc
annotate gcc/config/picochip/libgccExtras/lshrsi3.c @ 67:f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
| author | nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Tue, 22 Mar 2011 17:18:12 +0900 |
| parents | a06113de4d67 |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 | |
| 3 picoChip GCC support for 32-bit logical shift right. | |
| 4 | |
| 5 Copyright (C) 2003, 2004, 2005, 2008, 2009 Free Software Foundation, Inc. | |
|
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
6 Contributed by Picochip Ltd. |
| 0 | 7 Maintained by Daniel Towner (daniel.towner@picochip.com) |
| 8 | |
| 9 This file is free software; you can redistribute it and/or modify it | |
| 10 under the terms of the GNU General Public License as published by the | |
| 11 Free Software Foundation; either version 3, or (at your option) any | |
| 12 later version. | |
| 13 | |
| 14 This file is distributed in the hope that it will be useful, but | |
| 15 WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 17 General Public License for more details. | |
| 18 | |
| 19 Under Section 7 of GPL version 3, you are granted additional | |
| 20 permissions described in the GCC Runtime Library Exception, version | |
| 21 3.1, as published by the Free Software Foundation. | |
| 22 | |
| 23 You should have received a copy of the GNU General Public License and | |
| 24 a copy of the GCC Runtime Library Exception along with this program; | |
| 25 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
| 26 <http://www.gnu.org/licenses/>. */ | |
| 27 | |
| 28 typedef int HItype __attribute__ ((mode (HI))); | |
| 29 typedef unsigned int UHItype __attribute__ ((mode (HI))); | |
| 30 typedef unsigned int USItype __attribute__ ((mode (SI))); | |
| 31 | |
| 32 typedef struct USIstruct { | |
| 33 UHItype low, high; | |
| 34 } USIstruct; | |
| 35 | |
| 36 typedef union USIunion { | |
| 37 USItype l; | |
| 38 USIstruct s; | |
| 39 } USIunion; | |
| 40 | |
| 41 USItype __lshrsi3(USIunion value, HItype count) { | |
| 42 USIunion result; | |
| 43 int temp; | |
| 44 | |
| 45 /* Ignore a zero count until we get into the (count < 16) | |
| 46 clause. This is slightly slower when shifting by zero, but faster | |
| 47 and smaller in all other cases (due to the better scheduling | |
| 48 opportunities available by putting the test near computational | |
| 49 instructions. */ | |
| 50 | |
| 51 if (count < 16) { | |
| 52 /* Shift low and high words by the count. */ | |
| 53 result.s.low = value.s.low >> count; | |
| 54 result.s.high = value.s.high >> count; | |
| 55 | |
| 56 /* There is now a hole in the upper `count' bits of the low | |
| 57 word. Shift the lower `count' bits of the upper word into the | |
| 58 low word. This only works when count isn't zero. */ | |
| 59 if (count != 0) { | |
| 60 temp = value.s.high << (16 - count); | |
| 61 result.s.low |= temp; | |
| 62 } | |
| 63 | |
| 64 } else { | |
| 65 /* Shift the upper word of the source into the lower word of the | |
| 66 result, and zero the result's upper word. Note that we actually | |
| 67 ned to shift by (count - 16), but as we are only using the | |
| 68 bottom 4 bits, this is equivalent to shifting by count. */ | |
| 69 result.s.low = value.s.high >> count; | |
| 70 result.s.high = 0; | |
| 71 | |
| 72 } | |
| 73 | |
| 74 return result.l; | |
| 75 | |
| 76 } |