From 8ae3122d64ef1434b2b11b25cacd77d65663b3fa Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 9 Jun 2010 11:21:52 -0700 Subject: [PATCH] Unify instances of integer log2 Unify multiple open-coded instances of integer binary logarithm. Signed-off-by: H. Peter Anvin --- com32/include/ilog2.h | 48 +++++++++++++++++++++++++++++++++++++++++ com32/lib/sys/vesa/background.c | 4 ++-- com32/lib/sys/vesa/screencpy.c | 7 +----- core/fs/fat/fat.c | 9 ++------ 4 files changed, 53 insertions(+), 15 deletions(-) create mode 100644 com32/include/ilog2.h diff --git a/com32/include/ilog2.h b/com32/include/ilog2.h new file mode 100644 index 0000000..91a5057 --- /dev/null +++ b/com32/include/ilog2.h @@ -0,0 +1,48 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2010 Intel Corporation; author: H. Peter Anvin + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, + * copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom + * the Software is furnished to do so, subject to the following + * conditions: + * + * The above copyright notice and this permission notice shall + * be included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES + * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT + * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, + * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + * ----------------------------------------------------------------------- */ + +#ifndef _ILOG2_H +#define _ILOG2_H + +/* + * Computes floor(log2(x)) -- undefined for x = 0. + */ + +#include +#include + +static inline __constfunc uint32_t ilog2(uint32_t __v) +{ +# if __GNUC__ >= 4 + return __builtin_clz(__v) ^ 31; +# else + asm("bsrl %1,%0" : "=r" (__v) : "rm" (__v)); + return __v; +# endif +} + +#endif /* _ILOG2_H */ diff --git a/com32/lib/sys/vesa/background.c b/com32/lib/sys/vesa/background.c index 8d73239..9357746 100644 --- a/com32/lib/sys/vesa/background.c +++ b/com32/lib/sys/vesa/background.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include "vesa.h" #include "video.h" @@ -255,8 +256,7 @@ int vesacon_default_background(void) z = max(__vesa_info.mi.v_res, __vesa_info.mi.h_res) >> 1; z = ((z*z) >> 11) - 1; - asm("bsrl %1,%0" : "=r" (shft) : "rm" (z)); - shft++; + shft = ilog2(z) + 1; for (y = 0, dy = -(__vesa_info.mi.v_res >> 1); y < __vesa_info.mi.v_res; y++, dy++) { diff --git a/com32/lib/sys/vesa/screencpy.c b/com32/lib/sys/vesa/screencpy.c index 9740ea1..32dce9e 100644 --- a/com32/lib/sys/vesa/screencpy.c +++ b/com32/lib/sys/vesa/screencpy.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "vesa.h" #include "video.h" @@ -41,12 +42,6 @@ static struct win_info { int win_num; } wi; -static inline int __constfunc ilog2(unsigned int x) -{ - asm("bsrl %1,%0" : "=r"(x) : "rm"(x)); - return x; -} - void __vesacon_init_copy_to_screen(void) { struct vesa_mode_info *const mi = &__vesa_info.mi; diff --git a/core/fs/fat/fat.c b/core/fs/fat/fat.c index 9877a4d..54cd3b5 100644 --- a/core/fs/fat/fat.c +++ b/core/fs/fat/fat.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include "codepage.h" #include "fat_fs.h" @@ -729,12 +730,6 @@ static int vfat_load_config(void) return 0; } -static inline __constfunc uint32_t bsr(uint32_t num) -{ - asm("bsrl %1,%0" : "=r" (num) : "rm" (num)); - return num; -} - /* init. the fs meta data, return the block size in bits */ static int vfat_fs_init(struct fs_info *fs) { @@ -767,7 +762,7 @@ static int vfat_fs_init(struct fs_info *fs) sbi->root_size = root_dir_size(fs, &fat); sbi->data = sbi->root + sbi->root_size; - sbi->clust_shift = bsr(fat.bxSecPerClust); + sbi->clust_shift = ilog2(fat.bxSecPerClust); sbi->clust_byte_shift = sbi->clust_shift + fs->sector_shift; sbi->clust_mask = fat.bxSecPerClust - 1; sbi->clust_size = fat.bxSecPerClust << fs->sector_shift; -- 2.7.4