37 lines
1.1 KiB
C
37 lines
1.1 KiB
C
/* $NetBSD: intbits.c,v 1.1.1.1 2001/01/27 08:09:01 itojun Exp $ */
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/* Copyright (C) RSA Data Security, Inc. created 1990, 1996. This is an
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unpublished work protected as such under copyright law. This work
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contains proprietary, confidential, and trade secret information of
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RSA Data Security, Inc. Use, disclosure or reproduction without the
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express written authorization of RSA Data Security, Inc. is
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prohibited.
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*/
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#include "port_before.h"
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#include "global.h"
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#include "algae.h"
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#include "port_after.h"
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/* Return the number of bits in the canonical, positive integer.
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IntgerBits (0) = 0.
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*/
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unsigned int A_IntegerBits (integer, integerLen)
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unsigned char *integer;
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unsigned int integerLen;
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{
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unsigned char mask, byte;
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unsigned int bytes, bits;
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for (bytes = 0; bytes < integerLen && integer[bytes] == 0; bytes++);
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if (bytes == integerLen)
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return (0);
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/* Get byte to test and increment byte count for final calculation */
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byte = integer[bytes++];
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/* Get number of bits in most significant byte */
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for (bits = 8, mask = 0x80; (byte & mask) == 0; bits--, mask >>= 1);
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return (8 * (integerLen - bytes) + bits);
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}
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