AnaGram interim repo (temporary): checksum/dosum.c annotate

annotate checksum/dosum.c @ 21:1c9dac05d040

Add lint-style FALLTHROUGH annotations to fallthrough cases. (in the parse engine and thus the output code) Document this, because the old output causes warnings with gcc10.

author	David A. Holland
date	Mon, 13 Jun 2022 00:04:38 -0400
parents	3aa0f5a02342
children

rev	line source
0 13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	1 /*
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	2 * AnaGram, A System for Syntax Directed Programming
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	3 * Copyright 1993 Parsifal Software. All Rights Reserved.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	4 * Copyright 2006 David A. Holland. All Rights Reserved.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	5 * See the file COPYING for license and usage terms.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	6 *
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	7 * dosum.c - checksums.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	8 */
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	9
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	10 /*
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	11 * Fletcher's check-sum routines for AnaGram
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	12 *
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	13 * Freely adapted from routines published in Dr. Dobbs Journal
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	14 * May 1992, p. 64
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	15 *
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	16 * Revised as portable C in June 2006.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	17 */
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	18
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	19 #include <stdint.h>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	20 #include <string.h>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	21 #include <assert.h>
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	22
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	23 #include "bits.h"
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	24
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	25 struct sumstate {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	26 uint16_t k1, k2;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	27 };
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	28
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	29 static void sumstate_init(struct sumstate *s, size_t length) {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	30 s->k1 = (uint16_t) (length >> 16);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	31 s->k2 = (uint16_t) length;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	32
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	33 if (s->k1 == 0) s->k1++;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	34 if (s->k2 == 0) s->k2++;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	35 }
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	36
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	37 static void sumstate_sum(struct sumstate s, const void buf, size_t len) {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	38 const uint8_t *cb;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	39 unsigned i, n;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	40 uint16_t x;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	41
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	42 cb = buf;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	43 n = len/sizeof(uint16_t);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	44 for (i=0; i<n; i++) {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	45
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	46 // read one octet at a time so the byte order is deterministic
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	47 x = *cb++;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	48 x += ((uint16_t)*cb++) << 8;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	49
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	50 s->k1 += x;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	51 if (s->k1 < x) s->k1++;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	52 s->k2 += s->k1;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	53 if (s->k2 < s->k1) s->k2++;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	54 }
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	55 }
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	56
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	57 static uint32_t sumstate_finish(struct sumstate *s) {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	58 uint32_t sum;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	59
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	60 s->k1 ^= 0xffff;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	61 s->k2 ^= 0xffff;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	62 sum = 65535UL*s->k2 + s->k1;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	63
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	64 return sum;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	65 }
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	66
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	67 uint32_t dosum(const char *buf, size_t len, size_t skipstart, size_t skiplen) {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	68 struct sumstate s;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	69 size_t numwords;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	70
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	71 assert(skiplen%2==0);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	72 assert(skipstart==0 \|\| skipstart+skiplen <= len);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	73 sumstate_init(&s, len);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	74
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	75 /*
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	76 * It would be nice if we could count on skipstart being aligned.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	77 * But we can't. Nor is the filesize necessarily even.
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	78 *
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	79 * The followed mangled logic that rounds some things up matches
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	80 * what used to be done in an even uglier way.
11 3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	81 *
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	82 * To wit: if there's a skip area, we start after it and read pairs
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	83 * of octets, including a zero past the end of the file if the
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	84 * remaining data length after the skip area has odd size, so as to
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	85 * get the last byte. (The caller is responsible for making sure
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	86 * there's a zero there.) Then we read the beginning of the file up
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	87 * to the skip area, but round down so as to not read the first byte
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	88 * of the skip area if skipstart is odd. If skipstart is odd then we
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	89 * wedge in that last byte along with a zero.
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	90 *
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	91 * If there isn't a skip area, we read the whole thing in order,
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	92 * including the zero past the end if the size is odd.
0 13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	93 */
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	94
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	95 assert(sizeof(uint16_t)==2);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	96 numwords = (len+1)/2;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	97
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	98 if (skipstart > 0) {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	99 size_t p0 = skipstart+skiplen;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	100 size_t l0 = (numwords - p0/2) * 2;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	101 size_t p1 = 0;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	102 size_t l1 = (skipstart/2) * 2;
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	103
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	104 sumstate_sum(&s, buf+p0, l0);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	105 sumstate_sum(&s, buf+p1, l1);
11 3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	106 if (skipstart % 2 == 1) {
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	107 char tmp[2];
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	108
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	109 tmp[0] = buf[skipstart - 1];
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	110 tmp[1] = 0;
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	111 sumstate_sum(&s, tmp, 2);
3aa0f5a02342 Remove unused variable; fix what it was supposed to be doing. David A. Holland parents: 0 diff changeset	112 }
0 13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	113 }
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	114 else {
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	115 sumstate_sum(&s, buf, numwords * 2);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	116 }
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	117
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	118 return sumstate_finish(&s);
13d2b8934445 Import AnaGram (near-)release tree into Mercurial. David A. Holland parents: diff changeset	119 }

Mercurial > ~dholland > hg > ag > index.cgi

annotate checksum/dosum.c @ 21:1c9dac05d040