106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2007-2009 H. Peter Anvin - All Rights Reserved
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* Copyright 2009 Intel Corporation; author: H. Peter Anvin
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston MA 02110-1301, USA; either version 2 of the License, or
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* (at your option) any later version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* rllpack.inc
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*
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* Very simple RLL compressor/decompressor, used to pack binary structures
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* together.
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*
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* Format of leading byte
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* 1-128 = x verbatim bytes follow
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* 129-223 = (x-126) times subsequent byte
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* 224-255 = (x-224)*256+(next byte) times the following byte
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* 0 = end of data
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*
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* These structures are stored *in reverse order* in high memory.
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* High memory pointers point to one byte beyond the end.
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*/
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#include <com32.h>
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#include <stddef.h>
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#include <string.h>
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void rllpack(com32sys_t * regs)
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{
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uint8_t *i = (uint8_t *) (regs->esi.l);
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uint8_t *o = (uint8_t *) (regs->edi.l);
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size_t cnt = regs->ecx.l;
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size_t run, vrun, tcnt;
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uint8_t *hdr = NULL;
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uint8_t c;
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vrun = (size_t)-1;
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while (cnt) {
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c = *i;
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run = 1;
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tcnt = (cnt > 8191) ? 8191 : cnt;
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while (run < tcnt && i[run] == c)
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run++;
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if (run < 3) {
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if (vrun >= 128) {
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hdr = --o;
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vrun = 0;
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}
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*--o = c;
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*hdr = ++vrun;
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i++;
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cnt--;
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} else {
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if (run < 224 - 126) {
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*--o = run + 126;
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} else {
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o -= 2;
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*(uint16_t *) o = run + (224 << 8);
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}
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*--o = c;
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vrun = (size_t)-1;
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i += run;
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cnt -= run;
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}
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}
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*--o = 0;
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regs->esi.l = (size_t)i;
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regs->edi.l = (size_t)o;
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}
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void rllunpack(com32sys_t * regs)
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{
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uint8_t *i = (uint8_t *) regs->esi.l;
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uint8_t *o = (uint8_t *) regs->edi.l;
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uint8_t c;
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size_t n;
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while ((c = *--i)) {
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if (c <= 128) {
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while (c--)
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*o++ = *--i;
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} else {
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if (c < 224)
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n = c - 126;
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else
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n = ((c - 224) << 8) + *--i;
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c = *--i;
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while (n--)
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*o++ = c;
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}
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}
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regs->esi.l = (size_t)i;
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regs->ecx.l = (size_t)o - regs->edi.l;
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regs->edi.l = (size_t)o;
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}
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