China DOS Union

Originally posted by crshen at 2018-3-21 15:36:
Reply to rgwan:
After testing, the program can basically decompress the img of HD-copy, but there are some flaws in the source code:
1. The for loop of i is obviously wrong. Check the img format document, byte tracks; // total tracks - 1 ...

Thanks for pointing out the error. It has been modified and re-released on GitHub.... Because I have few images on hand, and this thing has always been in a temporary tool state, so I didn't care too much about code efficiency and unreproducible error problems.

In addition, for relatively new GCC, the judgment of escByte will actually be optimized and expanded to the outside. I wrote such code without thinking carefully.

Express my apologies to everyone.

That's really good!
Recently, I just came across an HD-COPY image file. I didn't find undisk, but I found this instead.

if not exist "dest" (md "dest")

for /f "tokens=*" %%i in ('dir/s/b/a-d *.img') do dehd-cmd.exe "dest\%%i"

Write any batch file, create a new .bat in the same directory as dehd-cmd.

Looking forward to a 64-bit support, support for IMG built-in directories (some old software extracts without the original directory), can be batch processed.

[ Last edited by kmcc123 on 2020-4-16 at 14:35 ]

The dehd - cmd.exe extraction program can smoothly extract IMG files in HDCPY format. Thanks to the hard - working code writing and sharing. I was just trying to find some DOS - related things when it came. In order to view on WIN10 conveniently and selectively extract the needed files, a shell program running on WIN10 is made and placed on the site, number 2430.

The program adds a right - click menu on WIN10. When the mouse right - clicks and selects a certain IMG and clicks, the shell program will extract the selected program to a temporary directory, and then hand it over to the 7z program to open the IMA file in the temporary folder, and the user can view the extraction, etc. When the 7z window is closed, the temporary files are deleted. Since I need it, I quickly wrote a few lines. It's a VB6 console program, and it works for me. There is an installation and usage instruction Readme.pdf in the compressed package.

```vb
Sub Form1_Command1_BN_Clicked(hWndForm As hWnd, hWndControl As hWnd)
Command1.Enabled = False
Dim sBuffer As String
Dim pnDataTrkMap As String
Dim splain As String '/* A standard track capacity */
Dim plain As Integer
Dim shdcopy As String '/* Store compressed track data */
Dim hdcopy As Integer
Dim nFinPos As Unsigned Long
Dim nDataLen As Unsigned Integer
Dim stempString As String
Dim iContFlag As Integer
Dim nTrackCount As Integer, nSecPerTrack As Integer, nBytesPerTrack As Integer _
,nActualImgAddr As Integer, nImgDataAddr As Integer, escByte As Integer, repeatByte As Integer, repeat As Integer

Open "1.IMG" For Binary Access Read As #1
Open "11.IMA" For Binary Access Write As #2

Seek #1, 1
sBuffer = Input(2, #1)

If ((sBuffer[0] = &Hff) And (sBuffer[1] = &H18)) Then
'Source img is an HD-COPY 2.0 Image
nActualImgAddr = 14 'skip volume label
nImgDataAddr = nActualImgAddr + 2 + 168 'Start position of data
Else
'Source img may be an HD-COPY 1.7 Image
nActualImgAddr = 0
nImgDataAddr = nActualImgAddr + 2 + 164
End If

Seek #1, nActualImgAddr + 1
sBuffer = Input(2, #1)

nTrackCount = sBuffer[0] 'Readout is (actual overall tracks - 1) e.g. (80-1) = 79
nSecPerTrack = sBuffer[1]
nBytesPerTrack = 512 * nSecPerTrack

'Debug.Print "nTrackCount and nSecPerTrack", nTrackCount, nSecPerTrack
'for a example, nSecPerTrack=15, and nBytesPerTrack = 512*nSecPerTrack， total disk = 512*nSecPerTrack*nTrackCount

Seek #1, nActualImgAddr + 2 + 1 '/* tracks_map */
pnDataTrkMap = Input(2 * (nTrackCount + 1), #1)

'Debug.Print Len(pnDataTrkMap)

plain = 0
hdcopy = 0
iContFlag = 0
splain = String(nBytesPerTrack, &H00) '/* A standard track capacity */
shdcopy = String(nBytesPerTrack, &H00) '/* Store compressed track data */

nFinPos = nImgDataAddr
'Debug.Print("Working hard,please wait...")
Seek #2, 1

For i As Integer = 0 To nTrackCount
For j As Integer = 0 To 1
iContFlag = 0
If (pnDataTrkMap[(i * 2) + j] <> &H01) Then '/* The mapped is an empty track */
splain = String(nBytesPerTrack, &H00)
Put #2,, splain


iContFlag = 1
End If

If iContFlag = 0 Then
Seek #1, nFinPos + 1
sBuffer = Input(2, #1)
nDataLen = sBuffer[0] + (sBuffer[1] Shl 8) '/* little endian */
shdcopy = Input(nDataLen, #1)

nFinPos = nFinPos + 2 + nDataLen
escByte = shdcopy[0]

For k As Integer = 1 To nDataLen - 1 '/* Decompress the track content of RLE compression */
If shdcopy[k] = escByte Then
k = k +1
repeatByte = shdcopy[k]: k = k +1
repeat = shdcopy[k]
For r As Integer = 0 To repeat - 1
splain[plain] = repeatByte: plain = plain + 1
Next r
Else
splain[plain] = shdcopy[k]: plain = plain + 1
End If
Next k
plain- = nBytesPerTrack
Put #2,, splain
End If
Next j
'Debug.Print i
Next i

Close #1
Close #2
MsgBox("Conversion completed!", "Information", MB_OK Or MB_ICONINFORMATION)
Command1.Enabled = True
End Sub
```

重写的代码使用了dehd - cmd.exe的原始代码，此外，当在最后一个磁道继续时出现的一个小错误通过简单关闭文件并返回0来强制程序结束以完成操作。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv)
{
FILE *fpin, *fpout;
unsigned int nBytesPerTrack;
unsigned char repeatByte;
unsigned char *buffer, *hdcopy, *plain, *pnDataTrkMap;
unsigned long nTrackCount, nSecPerTrack, nActualImgAddr, nImgDataAddr, escByte, repeat;
unsigned long nDataLen;
unsigned long nFinPos;
unsigned long i, j, k, r;

if (argc != 3)
{
fprintf(stderr, "Usage: %s <HD-COPY Image> <IMA plain floppy image>\n\n", argv);
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, "rb");
if (!fpin)
{
fprintf(stderr, "Can't open source HD-COPY image!\n");
exit(-1);
}

fpout = fopen(argv, "wb+");
if (!fpout)
{
fprintf(stderr, "Can't save plain floppy image!\n");
exit(-1);
}

buffer = (unsigned char *)malloc(2);

fseek(fpin, 0, SEEK_SET);
fread(buffer, 2, 1, fpin);
if (buffer == 0xff && buffer == 0x18)
{
printf("Source img is an HD-COPY 2.0 Image\n");
nActualImgAddr = 14; /* Skip the file header marked with the volume label */
nImgDataAddr = nActualImgAddr + 2 + 168; /* Start of track data */
}
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; /* total tracks - 1 */
nSecPerTrack = buffer;
nBytesPerTrack = 512 * nSecPerTrack;
printf("nTrackCount = %d, nSecPerTrack = %d\n", nTrackCount, nSecPerTrack);

pnDataTrkMap = (unsigned char *)malloc(2 * (nTrackCount + 1));
fseek(fpin, nActualImgAddr + 2, SEEK_SET); /* tracks_map */
fread(pnDataTrkMap, 2 * (nTrackCount + 1), 1, fpin);

plain = (unsigned char *)malloc(nBytesPerTrack); /* A standard track capacity */
hdcopy = (unsigned char *)malloc(nBytesPerTrack); /* Store compressed track data */
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 != 0x01) /* The map is an empty track */
{
memset(plain, 0x00, nBytesPerTrack);
fwrite(plain, nBytesPerTrack, 1, fpout);
if (i == nTrackCount)
{
fclose(fpin);
fclose(fpout);
return 0;
}
else
{
continue;
}
}

fseek(fpin, nFinPos, SEEK_SET);
fread(buffer, 2, 1, fpin);
nDataLen = buffer + (buffer << 8); /* little endian */
memset(hdcopy, 0x00, nBytesPerTrack);
fread(hdcopy, nDataLen, 1, fpin);
nFinPos = nFinPos + 2 + nDataLen;
escByte = hdcopy;
for (k = 1; k < nDataLen; k++) /* Decompress the track content of RLE compression */
{
if (hdcopy == escByte)
{
k++;
repeatByte = hdcopy;
repeat = hdcopy;
for (r = 0; r < repeat; r++)
{
*(plain++) = repeatByte;
}
}
else
{
*(plain++) = hdcopy;
}
}
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;
}