diff options
author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-08-19 03:12:28 +0000 |
---|---|---|
committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-08-19 03:12:28 +0000 |
commit | 1fd361a1ea06e44286c213ca1f814f49306fdc43 (patch) | |
tree | 64c8c96cf54d8718847339a403e5e67b922e8c3f /lib/util/bitreverse.h | |
download | netpbm-mirror-1fd361a1ea06e44286c213ca1f814f49306fdc43.tar.gz netpbm-mirror-1fd361a1ea06e44286c213ca1f814f49306fdc43.tar.xz netpbm-mirror-1fd361a1ea06e44286c213ca1f814f49306fdc43.zip |
Create Subversion repository
git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@1 9d0c8265-081b-0410-96cb-a4ca84ce46f8
Diffstat (limited to 'lib/util/bitreverse.h')
-rw-r--r-- | lib/util/bitreverse.h | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/lib/util/bitreverse.h b/lib/util/bitreverse.h new file mode 100644 index 00000000..b3f0ea13 --- /dev/null +++ b/lib/util/bitreverse.h @@ -0,0 +1,46 @@ +/* +** bitreverse.h +** +** This particular array seems to be useful in a lot of bitmap +** conversion programs. It's not used with standard libnetpbm PBM +** processing because bits are stored one per byte (or per word), for +** easier manipulation. But if you wanted to write, for example, a +** program to directly convert Sun raster format into X bitmaps, you +** could use this. It's also useful for the "packed PBM" libnetpbm +** functions. +** +** Of course, you could also use this fairly slick chunk of code: +** +** c = ((c >> 1) & 0x55) | ((c << 1) & 0xaa); +** c = ((c >> 2) & 0x33) | ((c << 2) & 0xcc); +** c = ((c >> 4) & 0x0f) | ((c << 4) & 0xf0); +*/ + +#ifndef _BITR_H_ +#define _BITR_H_ + +static unsigned char bitreverse[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}; + +#endif /*_BITR_H_*/ |