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BITREV.C@ cbe2c15

Last change on this file since cbe2c15 was 3ae31e9, checked in by Thomas Lopatic <thomas@…>, 7 years ago
Imported original source code.
Property mode set to `100755`
File size: 922 bytes

Rev	Line
[3ae31e9]	1	/*
	2	=============================================================================
	3	bitrev.c -- bit reverse function
	4	Version 1 -- 1987-03-24 -- D.N. Lynx Crowe
	5	=============================================================================
	6	*/
	7
	8	static int bitmask[] = {
	9
	10	0x0001, 0x0002, 0x0004, 0x0008,
	11	0x0010, 0x0020, 0x0040, 0x0080,
	12	0x0100, 0x0200, 0x0400, 0x0800,
	13	0x1000, 0x2000, 0x4000, 0x8000
	14	};
	15
	16	/*
	17	=============================================================================
	18	bitrev(bitsin, nbits) -- reverses the rightmost nbits of bitsin.
	19
	20	Any bits to the left of the reversed bits in the result will be zeros.
	21	=============================================================================
	22	*/
	23
	24	int
	25	bitrev(bitsin, nbits)
	26	int bitsin, nbits;
	27	{
	28	int m, n;
	29
	30	n = 0;
	31
	32	for (m = 0; m < nbits; m++)
	33	if (bitsin & bitmask[m])
	34	n \|= bitmask[nbits-1-m];
	35
	36	return(n);
	37	}
	38

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