>Thanks Manu -
> I have made the appropriate changes. The original code was GPLd but I
>have
>contacted the original Author - Jack Kelliher who has agreed to allow the
>code
>to to be LGPLd with the dvb_core library. The comments in dvb_math.c reflect
>that as well. Let me know if I missed anything with this patch.
>
>Rusty
Sorry to have concurrenced you, but manu told me to create one. Anyway, the
error (not the accurancy!!) is now < 0.047%.
Christoph
unsigned char msbtable[256] = {
0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7};
unsigned short logtable[256] = {0x0000, 0x0171, 0x02e0, 0x044e, 0x05ba, 0x0725,
0x088e, 0x09f7, 0x0b5d, 0x0cc3, 0x0e27, 0x0f8a, 0x10eb, 0x124b, 0x13aa, 0x1508,
0x1664, 0x17bf, 0x1919, 0x1a71, 0x1bc8, 0x1d1e, 0x1e73, 0x1fc6, 0x2119, 0x226a,
0x23ba, 0x2508, 0x2656, 0x27a2, 0x28ed, 0x2a37, 0x2b80, 0x2cc8, 0x2e0f, 0x2f54,
0x3098, 0x31dc, 0x331e, 0x345f, 0x359f, 0x36de, 0x381b, 0x3958, 0x3a94, 0x3bce,
0x3d08, 0x3e41, 0x3f78, 0x40af, 0x41e4, 0x4319, 0x444c, 0x457f, 0x46b0, 0x47e1,
0x4910, 0x4a3f, 0x4b6c, 0x4c99, 0x4dc5, 0x4eef, 0x5019, 0x5142, 0x526a, 0x5391,
0x54b7, 0x55dc, 0x5700, 0x5824, 0x5946, 0x5a68, 0x5b89, 0x5ca8, 0x5dc7, 0x5ee5,
0x6003, 0x611f, 0x623a, 0x6355, 0x646f, 0x6588, 0x66a0, 0x67b7, 0x68ce, 0x69e4,
0x6af8, 0x6c0c, 0x6d20, 0x6e32, 0x6f44, 0x7055, 0x7165, 0x7274, 0x7383, 0x7490,
0x759d, 0x76aa, 0x77b5, 0x78c0, 0x79ca, 0x7ad3, 0x7bdb, 0x7ce3, 0x7dea, 0x7ef0,
0x7ff6, 0x80fb, 0x81ff, 0x8302, 0x8405, 0x8507, 0x8608, 0x8709, 0x8809, 0x8908,
0x8a06, 0x8b04, 0x8c01, 0x8cfe, 0x8dfa, 0x8ef5, 0x8fef, 0x90e9, 0x91e2, 0x92db,
0x93d2, 0x94ca, 0x95c0, 0x96b6, 0x97ab, 0x98a0, 0x9994, 0x9a87, 0x9b7a, 0x9c6c,
0x9d5e, 0x9e4f, 0x9f3f, 0xa02e, 0xa11e, 0xa20c, 0xa2fa, 0xa3e7, 0xa4d4, 0xa5c0,
0xa6ab, 0xa796, 0xa881, 0xa96a, 0xaa53, 0xab3c, 0xac24, 0xad0c, 0xadf2, 0xaed9,
0xafbe, 0xb0a4, 0xb188, 0xb26c, 0xb350, 0xb433, 0xb515, 0xb5f7, 0xb6d9, 0xb7ba,
0xb89a, 0xb97a, 0xba59, 0xbb38, 0xbc16, 0xbcf4, 0xbdd1, 0xbead, 0xbf8a, 0xc065,
0xc140, 0xc21b, 0xc2f5, 0xc3cf, 0xc4a8, 0xc580, 0xc658, 0xc730, 0xc807, 0xc8de,
0xc9b4, 0xca8a, 0xcb5f, 0xcc34, 0xcd08, 0xcddc, 0xceaf, 0xcf82, 0xd054, 0xd126,
0xd1f7, 0xd2c8, 0xd399, 0xd469, 0xd538, 0xd607, 0xd6d6, 0xd7a4, 0xd872, 0xd93f,
0xda0c, 0xdad9, 0xdba5, 0xdc70, 0xdd3b, 0xde06, 0xded0, 0xdf9a, 0xe063, 0xe12c,
0xe1f5, 0xe2bd, 0xe385, 0xe44c, 0xe513, 0xe5d9, 0xe69f, 0xe765, 0xe82a, 0xe8ef,
0xe9b3, 0xea77, 0xeb3b, 0xebfe, 0xecc1, 0xed83, 0xee45, 0xef06, 0xefc8, 0xf088,
0xf149, 0xf209, 0xf2c8, 0xf387, 0xf446, 0xf505, 0xf5c3, 0xf680, 0xf73e, 0xf7fb,
0xf8b7, 0xf973, 0xfa2f, 0xfaea, 0xfba5, 0xfc60, 0xfd1a, 0xfdd4, 0xfe8e, 0xff47};
unsigned int intlog2(unsigned int value) {
unsigned int msb;
if(value >= (1 << 16)) { // value >= 2^16
if(value >= (1 << 24)) { // value >= 2^24
msb = 24 + msbtable[value >> 24];
} else { // 2^16 <= value < 2^24
msb = 16 + msbtable[value >> 16];
}
} else { // value < 2^16
if(value >= (1 << 8)) { // 2^8 <= value < 2^16
msb = 8 + msbtable[value >> 8];
} else { // value < 2^8
msb = msbtable[value];
}
}
/* // basic variant
// now msb is the rounded down log2(value)
// returns: 000000000000xxxx , where x msb and error < 36.9%
return msb; */
// extended variant
// returns: log2(value) * 2^16
int fract = value << (31 - msb); // msb is now the highest bit in fract
return (msb << 16) + logtable[(fract >> 23) & 0xff];
}
unsigned int intlog10(unsigned int value) {
// returns: log10(value) * 2^28
return intlog2(value) * 1233;
}
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