『第
14 楼』:
首先感谢rgwan分享源码，这里是我修改的DOS版本，可用TC2.0或BC3.1编译。
由于DOS内存限制，不可能像保护模式下那样直接申请一个大内存，故数据解码需频繁进行文件读写，磁盘IO速度自然比不上内存，效率较CMD版要差些。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(int argc, char *argv[])
{
FILE *fpin, *fpout;
unsigned char *buffer, *hdcopy, *plain, *pnDataTrkMap;
int nTrackCount, nSecPerTrack, nBytesPerTrack, nActualImgAddr, nImgDataAddr, escByte, repeatByte, repeat;
unsigned int nDataLen;
unsigned long nFinPos;
int i, j, k, r;
if (argc != 3)
{
fprintf(stderr, "Usage: %s <HD-COPY Image> <IMA plain floppy image>\n\n", argv[0]);
fprintf(stderr, "This small tool decompress HD-COPY image to plain floppy image.\n");
fprintf(stderr, "Therefore, you can use old HD-COPY img on modern PC or Virtual Machine.\n\n");
fprintf(stderr, "Zhiyuan Wan <h@iloli.bid> 2018, License WTFPL.\nAlgorithm analyze from <https://github.com/ciel-yu/devnotes>. Thanks him!\n");
fprintf(stderr, "Modified to suit old DOS by crshen <crshen@qq.com>.\n\n");
exit(-1);
}
fpin = fopen(argv[1], "rb");
if (!fpin)
{
fprintf(stderr, "Can't open source HD-COPY image!\n");
exit(-1);
}
fpout = fopen(argv[2], "wb+");
if (!fpout)
{
fprintf(stderr, "Can't save plain floppy image!\n");
exit(-1);
}
buffer = malloc(2);
fseek(fpin, 0, SEEK_SET);
fread(buffer, 2, 1, fpin);
if (buffer[0] == 0xff && buffer[1] == 0x18)
{
printf("Source img is an HD-COPY 2.0 Image\n");
nActualImgAddr = 14; /* 跳过标有卷标的文件头 */
nImgDataAddr = nActualImgAddr + 2 + 168; /* 磁道数据起始 */
}
else
{
printf("Source img may be an HD-COPY 1.7 Image\n");
nActualImgAddr = 0;
nImgDataAddr = nActualImgAddr + 2 + 164;
}
fseek(fpin, nActualImgAddr, SEEK_SET);
fread(buffer, 2, 1, fpin);
nTrackCount = buffer[0]; /* total tracks - 1 */
nSecPerTrack = buffer[1];
nBytesPerTrack = 512 * nSecPerTrack;
printf("nTrackCount = %d, nSecPerTrack = %d\n", nTrackCount, nSecPerTrack);
pnDataTrkMap = malloc(2 * (nTrackCount + 1));
fseek(fpin, nActualImgAddr + 2, SEEK_SET); /* tracks_map */
fread(pnDataTrkMap, 2 * (nTrackCount + 1), 1, fpin);
plain = malloc(nBytesPerTrack); /* 一个标准磁道容量 */
hdcopy = malloc(nBytesPerTrack); /* 存放压缩磁道数据 */
nFinPos = nImgDataAddr;
printf("Working hard,please wait...\n");
fseek(fpout, 0, SEEK_SET);
for (i = 0; i <= nTrackCount; i++)
{
for (j = 0; j < 2; j++)
{
if (pnDataTrkMap[(i * 2) + j] != 0x01) /* 映射为空磁道 */
{
memset(plain, 0x00, nBytesPerTrack);
fwrite(plain, nBytesPerTrack, 1, fpout);
continue;
}
fseek(fpin, nFinPos, SEEK_SET);
fread(buffer, 2, 1, fpin);
nDataLen = buffer[0] + (buffer[1] << 8); /* little endian */
memset(hdcopy, 0x00, nBytesPerTrack);
fread(hdcopy, nDataLen, 1, fpin);
nFinPos = nFinPos + 2 + nDataLen;
escByte = hdcopy[0];
for (k = 1; k < nDataLen; k++) /* RLE压缩的磁道内容解压 */
{
if (hdcopy[k] == escByte)
{
k++;
repeatByte = hdcopy[k++];
repeat = hdcopy[k];
for (r = 0; r < repeat; r++)
{
*(plain++) = repeatByte;
}
}
else
{
*(plain++) = hdcopy[k];
}
}
plain -= nBytesPerTrack;
fwrite(plain, nBytesPerTrack, 1, fpout);
}
}
fclose(fpin);
fclose(fpout);
free(hdcopy);
free(buffer);
free(pnDataTrkMap);
free(plain);
printf("Decompress operation completed.\n");
return 0;
} [ Last edited by crshen on 2018-3-21 at 16:27 ]
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