82 lines
2.0 KiB
C
82 lines
2.0 KiB
C
/*
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* Copyright (C) 2006 Apple Computer, Inc. All rights reserved.
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* Copyright (C) 2007-2012 Apple Inc. All rights reserved.
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*
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* This document is the property of Apple Computer, Inc.
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* It is considered confidential and proprietary.
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*
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* This document may not be reproduced or transmitted in any form,
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* in whole or in part, without the express written permission of
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* Apple Inc.
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*/
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#include <sys.h>
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#include <arch.h>
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#include <sys/types.h>
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#include <lib/cksum.h>
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#if (ARCH_ARMv7 && WITH_VFP) || defined(__arm64__)
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extern uint32_t adler32_vec(uint32_t, uint32_t, const uint8_t *, long);
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#endif
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#define BASE 65521L /* largest prime smaller than 65536 */
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#define NMAX 5000
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// NMAX (was 5521) the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
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#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
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#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
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#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
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#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
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#define DO16(buf) DO8(buf,0); DO8(buf,8);
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uint32_t adler32(const uint8_t *buf, long len)
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{
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uint32_t s1 = 1; // adler & 0xffff;
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uint32_t s2 = 0; // (adler >> 16) & 0xffff;
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int k;
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#if (ARCH_ARMv7 && WITH_VFP) || defined(__arm64__)
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/* align buf to 16-byte boundary */
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while ((int)buf & 15) { /* not on a 16-byte boundary */
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len--;
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s1 += *buf++;
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s2 += s1;
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s1 %= BASE;
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s2 %= BASE;
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}
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if (len > 16) {
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#if WITH_VFP_ALWAYS_ON
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return adler32_vec(s1, s2, buf, len);
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#else
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bool fp_enabled;
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uint32_t result;
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fp_enabled = arch_task_fp_enable(true);
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result = adler32_vec(s1, s2, buf, len);
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arch_task_fp_enable(fp_enabled);
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return result;
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#endif // WITH_VFP_ALWAYS_ON
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}
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#endif
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while (len > 0) {
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k = len < NMAX ? len : NMAX;
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len -= k;
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while (k >= 16) {
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DO16(buf);
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buf += 16;
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k -= 16;
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}
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if (k != 0) do {
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s1 += *buf++;
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s2 += s1;
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} while (--k);
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s1 %= BASE;
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s2 %= BASE;
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}
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return (s2 << 16) | s1;
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}
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