path: root/lib/bitrev.c
diff options
authorMike Dunn <>2013-04-12 11:59:17 -0700
committerMarek Vasut <>2013-05-05 23:47:04 +0200
commit0dd9c7a924f9a7b15fdb15d9005fd5506965f49f (patch)
tree710ead4a7e11dcf2e1ff2088c51170fa0589206f /lib/bitrev.c
parent5ed6f447af60aabd2669d913f673793c1ce48f47 (diff)
lib: import bitrev library from the linux kernel
This patch adds the bitrev library from the linux kernel. This is a simple algorithm that uses an 8 bit look-up table to reverse the bits in data types of 8, 16, or 32 bit widths. The docg4 nand flash driver uses it. [port from linux kernel v3.9 commit 7ee32a6d30d1c8a3b7a07a6269da8f0a08662927] [originally added: v2.6.20 by commit a5cfc1ec58a07074dacb6aa8c79eff864c966d12] Signed-off-by: Mike Dunn <>
Diffstat (limited to 'lib/bitrev.c')
1 files changed, 59 insertions, 0 deletions
diff --git a/lib/bitrev.c b/lib/bitrev.c
new file mode 100644
index 0000000000..160021a37f
--- /dev/null
+++ b/lib/bitrev.c
@@ -0,0 +1,59 @@
+ * This file is released under the terms of GPL v2 and any later version.
+ * See the file COPYING in the root directory of the source tree for details.
+ *
+ * Based on bitrev from the Linux kernel, by Akinobu Mita
+ */
+#include <linux/types.h>
+#include <linux/bitrev.h>
+const u8 byte_rev_table[256] = {
+ 0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
+ 0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
+ 0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
+ 0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
+ 0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
+ 0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
+ 0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
+ 0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
+ 0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
+ 0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
+ 0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
+ 0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
+ 0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
+ 0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
+ 0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
+ 0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
+ 0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
+ 0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
+ 0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
+ 0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
+ 0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
+ 0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
+ 0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
+ 0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
+ 0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
+ 0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
+ 0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
+ 0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
+ 0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
+ 0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
+ 0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
+ 0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff,
+u16 bitrev16(u16 x)
+ return (bitrev8(x & 0xff) << 8) | bitrev8(x >> 8);
+ * bitrev32 - reverse the order of bits in a u32 value
+ * @x: value to be bit-reversed
+ */
+u32 bitrev32(u32 x)
+ return (bitrev16(x & 0xffff) << 16) | bitrev16(x >> 16);
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