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Added support for multimedia .ajz files

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@4199 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Björn Stenberg 2004-01-08 00:22:27 +00:00
parent a55bfd9204
commit 7f749b4689
1 changed files with 95 additions and 10 deletions
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105
tools/descramble.c
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@ -26,11 +26,14 @@ int main (int argc, char** argv)
unsigned char *inbuf,*outbuf;
unsigned char *iname = argv[1];
unsigned char *oname = argv[2];
unsigned char header[32];
int headerlen = 6;
int descramble = 1;
FILE* file;
if (argc < 3) {
printf("usage: %s [-fm] [-v2] <input file> <output file>\n",argv[0]);
printf("usage: %s [-fm] [-v2] [-mm] <input file> <output file>\n",
argv[0]);
return -1;
}
@ -39,6 +42,13 @@ int main (int argc, char** argv)
iname = argv[2];
oname = argv[3];
}
if (!strcmp(argv[1], "-mm")) {
headerlen = 16;
iname = argv[2];
oname = argv[3];
descramble = 0;
}
/* open file and check size */
file = fopen(iname,"rb");
@ -48,7 +58,13 @@ int main (int argc, char** argv)
}
fseek(file,0,SEEK_END);
length = ftell(file) - headerlen; /* skip header */
fseek(file,headerlen,SEEK_SET);
fseek(file,0,SEEK_SET);
i = fread(header, 1, headerlen, file);
if ( !i ) {
perror(iname);
return -1;
}
inbuf = malloc(length);
outbuf = malloc(length);
if ( !inbuf || !outbuf ) {
@ -64,15 +80,84 @@ int main (int argc, char** argv)
}
fclose(file);
/* descramble */
slen = length/4;
for (i = 0; i < length; i++) {
unsigned long addr = ((i % slen) << 2) + i/slen;
unsigned char data = inbuf[i];
data = ~((data >> 1) | ((data << 7) & 0x80)); /* poor man's ROR */
outbuf[addr] = data;
if (descramble) {
/* descramble */
slen = length/4;
for (i = 0; i < length; i++) {
unsigned long addr = ((i % slen) << 2) + i/slen;
unsigned char data = inbuf[i];
data = ~((data >> 1) | ((data << 7) & 0x80)); /* poor man's ROR */
outbuf[addr] = data;
}
}
else {
void* tmpptr;
unsigned int j=0;
int stringlen = 32;
int unpackedsize;
unsigned char xorstring[32];
unpackedsize = ((unsigned int*)header)[1];
length = ((unsigned int*)header)[2];
/* calculate the xor string used */
for (i=0; i<stringlen; i++) {
int top=0, topchar=0, c;
int bytecount[256];
memset(bytecount, 0, sizeof(bytecount));
/* gather byte frequency statistics */
for (c=i; c<length; c+=stringlen)
bytecount[inbuf[c]]++;
/* find the most frequent byte */
for (c=0; c<256; c++) {
if (bytecount[c] > top) {
top = bytecount[c];
topchar = c;
}
}
xorstring[i] = topchar;
}
printf("XOR string: %.*s\n", stringlen, xorstring);
/* xor the buffer */
for (i=0; i<length; i++)
outbuf[i] = inbuf[i] ^ xorstring[i & (stringlen-1)];
/* unpack */
tmpptr = realloc(inbuf, unpackedsize);
memset(tmpptr, 0, unpackedsize);
inbuf = outbuf;
outbuf = tmpptr;
for (i=0; i<length;) {
int bit;
int head = inbuf[i++];
for (bit=0; bit<8 && i<length; bit++) {
if (head & (1 << (bit))) {
outbuf[j++] = inbuf[i++];
}
else {
int x;
int byte1 = inbuf[i];
int byte2 = inbuf[i+1];
int count = (byte2 & 0x0f) + 3;
int src =
(j & 0xfffff000) + (byte1 | ((byte2 & 0xf0)<<4)) + 18;
if (src > j)
src -= 0x1000;
for (x=0; x<count; x++)
outbuf[j++] = outbuf[src+x];
i += 2;
}
}
}
length = j;
}
/* write file */
file = fopen(oname,"wb");
if ( !file ) {