47 lines
1.6 KiB
C
47 lines
1.6 KiB
C
/* bitreverse.c
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*
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* Mirror the bits of an unsigned character so that b0 -> b7, b1 -> b6 etc.
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*
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* (C) 1998 Morten Rolland
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*/
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static unsigned char bitreverse[256] = {
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0x00,0x80,0x40,0xc0,0x20,0xa0,0x60,0xe0,
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0x10,0x90,0x50,0xd0,0x30,0xb0,0x70,0xf0,
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0x08,0x88,0x48,0xc8,0x28,0xa8,0x68,0xe8,
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0x18,0x98,0x58,0xd8,0x38,0xb8,0x78,0xf8,
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0x04,0x84,0x44,0xc4,0x24,0xa4,0x64,0xe4,
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0x14,0x94,0x54,0xd4,0x34,0xb4,0x74,0xf4,
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0x0c,0x8c,0x4c,0xcc,0x2c,0xac,0x6c,0xec,
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0x1c,0x9c,0x5c,0xdc,0x3c,0xbc,0x7c,0xfc,
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0x02,0x82,0x42,0xc2,0x22,0xa2,0x62,0xe2,
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0x12,0x92,0x52,0xd2,0x32,0xb2,0x72,0xf2,
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0x0a,0x8a,0x4a,0xca,0x2a,0xaa,0x6a,0xea,
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0x1a,0x9a,0x5a,0xda,0x3a,0xba,0x7a,0xfa,
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0x06,0x86,0x46,0xc6,0x26,0xa6,0x66,0xe6,
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0x16,0x96,0x56,0xd6,0x36,0xb6,0x76,0xf6,
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0x0e,0x8e,0x4e,0xce,0x2e,0xae,0x6e,0xee,
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0x1e,0x9e,0x5e,0xde,0x3e,0xbe,0x7e,0xfe,
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0x01,0x81,0x41,0xc1,0x21,0xa1,0x61,0xe1,
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0x11,0x91,0x51,0xd1,0x31,0xb1,0x71,0xf1,
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0x09,0x89,0x49,0xc9,0x29,0xa9,0x69,0xe9,
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0x19,0x99,0x59,0xd9,0x39,0xb9,0x79,0xf9,
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0x05,0x85,0x45,0xc5,0x25,0xa5,0x65,0xe5,
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0x15,0x95,0x55,0xd5,0x35,0xb5,0x75,0xf5,
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0x0d,0x8d,0x4d,0xcd,0x2d,0xad,0x6d,0xed,
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0x1d,0x9d,0x5d,0xdd,0x3d,0xbd,0x7d,0xfd,
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0x03,0x83,0x43,0xc3,0x23,0xa3,0x63,0xe3,
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0x13,0x93,0x53,0xd3,0x33,0xb3,0x73,0xf3,
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0x0b,0x8b,0x4b,0xcb,0x2b,0xab,0x6b,0xeb,
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0x1b,0x9b,0x5b,0xdb,0x3b,0xbb,0x7b,0xfb,
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0x07,0x87,0x47,0xc7,0x27,0xa7,0x67,0xe7,
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0x17,0x97,0x57,0xd7,0x37,0xb7,0x77,0xf7,
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0x0f,0x8f,0x4f,0xcf,0x2f,0xaf,0x6f,0xef,
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0x1f,0x9f,0x5f,0xdf,0x3f,0xbf,0x7f,0xff
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};
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unsigned char bitrev(unsigned char v)
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{
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return bitreverse[v];
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}
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