[syslinux:pathbased] Unify instances of integer log2

[syslinux-bot for H. Peter Anvin]

Commit-ID:  8ae3122d64ef1434b2b11b25cacd77d65663b3fa
Gitweb:     http://syslinux.zytor.com/commit/8ae3122d64ef1434b2b11b25cacd77d65663b3fa
Author:     H. Peter Anvin <hpa at linux.intel.com>
AuthorDate: Wed, 9 Jun 2010 11:21:52 -0700
Committer:  H. Peter Anvin <hpa at linux.intel.com>
CommitDate: Wed, 9 Jun 2010 11:26:22 -0700

Unify instances of integer log2

Unify multiple open-coded instances of integer binary logarithm.

Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>


---
 com32/{mboot/syslinux.c => include/ilog2.h} |   27 +++++++++++++++------------
 com32/lib/sys/vesa/background.c             |    4 ++--
 com32/lib/sys/vesa/screencpy.c              |    7 +------
 core/fs/fat/fat.c                           |    9 ++-------
 4 files changed, 20 insertions(+), 27 deletions(-)

diff --git a/com32/mboot/syslinux.c b/com32/include/ilog2.h
similarity index 79%
copy from com32/mboot/syslinux.c
copy to com32/include/ilog2.h
index 7de3853..91a5057 100644
--- a/com32/mboot/syslinux.c
+++ b/com32/include/ilog2.h
@@ -25,21 +25,24 @@
  *
  * ----------------------------------------------------------------------- */
 
+#ifndef _ILOG2_H
+#define _ILOG2_H
+
 /*
- * syslinux.c
- *
- * Syslinux-specific information for the kernel
+ * Computes floor(log2(x)) -- undefined for x = 0.
  */
 
-#include <syslinux/config.h>
-#include "mboot.h"
+#include <klibc/compiler.h>
+#include <stdint.h>
 
-void mboot_syslinux_info(void)
+static inline __constfunc uint32_t ilog2(uint32_t __v)
 {
-    const struct syslinux_version *sv;
-
-    sv = syslinux_version();
-    mbinfo.boot_loader_name = map_string(sv->version_string);
-    if (mbinfo.boot_loader_name)
-	mbinfo.flags |= MB_INFO_BOOT_LOADER_NAME;
+# 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 <sys/stat.h>
 #include <minmax.h>
 #include <stdbool.h>
+#include <ilog2.h>
 #include <syslinux/loadfile.h>
 #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 <klibc/compiler.h>
 #include <string.h>
 #include <com32.h>
+#include <ilog2.h>
 #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 <core.h>
 #include <disk.h>
 #include <fs.h>
+#include <ilog2.h>
 #include <klibc/compiler.h>
 #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;