126 lines
2.2 KiB
C
126 lines
2.2 KiB
C
/* Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. */
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/* Copyright (c) 1988 AT&T */
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/* All Rights Reserved */
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/* THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF */
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/* UNIX System Laboratories, Inc. */
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/* The copyright notice above does not evidence any */
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/* actual or intended publication of such source code. */
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/* #ident "@(#)sccs:lib/comobj/encode.c 1.1" */
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#ident "$Revision: 1.3 $"
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# include "../../hdr/defines.h"
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/* ENC is the basic 1 character encoding function to make a char printing */
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#define ENC(c) (((c) & 077) + ' ')
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/* single character decode */
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#define DEC(c) (((c) - ' ') & 077)
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void encode(),e_outdec(),decode(),d_outdec();
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void
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encode(infile,outfile)
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FILE *infile;
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FILE *outfile;
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{
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char buf[80];
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int i,n;
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for (;;)
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{
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/* 1 (up to) 45 character line */
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n = fr(infile, buf, 45);
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putc(ENC(n), outfile);
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for (i=0; i<n; i += 3)
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e_outdec(&buf[i], outfile);
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putc('\n', outfile);
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if (n <= 0)
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break;
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}
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}
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/*
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* output one group of 3 bytes, pointed at by p, on file f.
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*/
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void
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e_outdec(p, f)
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char *p;
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FILE *f;
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{
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int c1, c2, c3, c4;
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c1 = *p >> 2;
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c2 = (*p << 4) & 060 | (p[1] >> 4) & 017;
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c3 = (p[1] << 2) & 074 | (p[2] >> 6) & 03;
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c4 = p[2] & 077;
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putc(ENC(c1), f);
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putc(ENC(c2), f);
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putc(ENC(c3), f);
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putc(ENC(c4), f);
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}
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void
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decode(istr,outfile)
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char *istr;
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FILE *outfile;
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{
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char *bp;
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int n;
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n = DEC(istr[0]);
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if (n <= 0)
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return;
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bp = &istr[1];
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while (n > 0) {
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d_outdec(bp, outfile, n);
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bp += 4;
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n -= 3;
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}
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}
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/*
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* output a group of 3 bytes (4 input characters).
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* the input chars are pointed to by p, they are to
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* be output to file f. n is used to tell us not to
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* output all of them at the end of the file.
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*/
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void
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d_outdec(p, f, n)
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char *p;
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FILE *f;
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int n;
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{
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int c1, c2, c3;
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c1 = DEC(*p) << 2 | DEC(p[1]) >> 4;
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c2 = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
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c3 = DEC(p[2]) << 6 | DEC(p[3]);
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if (n >= 1)
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putc(c1, f);
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if (n >= 2)
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putc(c2, f);
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if (n >= 3)
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putc(c3, f);
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}
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/* fr: like read but stdio */
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int
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fr(fd, buf, cnt)
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FILE *fd;
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char *buf;
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int cnt;
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{
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int c, i;
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for (i=0; i<cnt; i++) {
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c = getc(fd);
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if (c == EOF)
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return(i);
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buf[i] = c;
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}
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return (cnt);
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}
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