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[pngzop] Added pngihdr.c and pngiend.c

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This commit is contained in:
Glenn Randers-Pehrson
2013-03-06 19:35:11 -06:00
parent 45bcb5ddd3
commit f35bac9bdd
2 changed files with 210 additions and 0 deletions
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112
pngiend.c Normal file
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#include <stdio.h>
/* Copyright 2013 Glenn Randers-Pehrson */
/* Usage:
* pngiend.exe < file.png > file.iend
*
* file.iend is the image datastream, minus everything through the
* last IDAT chunk.
*/
main()
{
unsigned int c;
unsigned int i;
unsigned int len[5];
unsigned int length;
unsigned int mode;
unsigned int name[5];
len[4]='\0';
name[4]='\0';
mode=0; /* Looking for IDAT */
/* Skip 8-byte signature */
for (i=8; i; i--)
{
c=getchar();
if (c == EOF)
break;
}
for (;;)
{
/* read length */
len[0]=getchar();
if (len[0] == EOF)
break;
len[1]=getchar();
len[2]=getchar();
len[3]=getchar();
if (len[3] == EOF)
break;
length=len[0]<<24 | len[1]<<16 | len[2]<< 8 | len[3];
/* read chunkname */
name[0]=getchar();
name[1]=getchar();
name[2]=getchar();
name[3]=getchar();
if (name[3] == EOF)
break;
if (name[0] == 'I' && name[1] == 'D' && name[2] == 'A' && \
name[3] == 'T')
{
if (mode == 0)
mode = 1; /* found IDAT */
}
else
{
if (mode == 1)
mode = 2; /* found chunk after IDAT */
}
if (mode == 2)
{
/* copy the length bytes */
putchar(len[0]);
putchar(len[1]);
putchar(len[2]);
putchar(len[3]);
/* copy the name bytes */
putchar(name[0]);
putchar(name[1]);
putchar(name[2]);
putchar(name[3]);
}
/* skip or copy the data bytes */
for (i=length; i; i--)
{
c=getchar();
if (c == EOF)
break;
if (mode == 2)
putchar(c);
}
if (c == EOF)
break;
/* skip or copy crc bytes */
for (i=4; i; i--)
{
c=getchar();
if (c == EOF)
break;
if (mode == 2)
putchar(c);
}
if (c == EOF)
break;
if (name[0] == 'I' && name[1] == 'E' && name[2] == 'N' && \
name[3] == 'D')
{
break;
}
}
}

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pngihdr.c Normal file
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#include <stdio.h>
/* Copyright 2013 Glenn Randers-Pehrson */
/* Usage:
* pngidat.exe < file.png > file.ihdr
*
* file.ihdr is the image datastream, with the PNG signature bytes
* and all chunks up to the first IDAT.
*/
main()
{
unsigned int i;
unsigned int len[5];
unsigned int name[5];
unsigned int c;
len[4]='\0';
name[4]='\0';
/* Copy 8-byte signature */
for (i=8; i; i--)
{
c=getchar();
if (c == EOF)
break;
putchar(c);
}
for (;;)
{
/* read length */
unsigned int length;
len[0]=getchar();
if (len[0] == EOF)
break;
len[1]=getchar();
len[2]=getchar();
len[3]=getchar();
if (len[3] == EOF)
break;
length=len[0]<<24 | len[1]<<16 | len[2] << 8 | len[3];
/* read chunkname */
name[0]=getchar();
name[1]=getchar();
name[2]=getchar();
name[3]=getchar();
if (name[3] == EOF)
break;
if (name[0] == 'I' && name[1] == 'D' && name[2] == 'A' && name[3] == 'T')
break;
/* copy the length bytes */
putchar(len[0]);
putchar(len[1]);
putchar(len[2]);
putchar(len[3]);
/* copy the name bytes */
putchar(name[0]);
putchar(name[1]);
putchar(name[2]);
putchar(name[3]);
/* copy the data bytes */
for (i=length; i; i--)
{
c=getchar();
if (c == EOF)
break;
putchar(c);
}
if (c == EOF)
break;
/* copy crc bytes */
for (i=4; i; i--)
{
c=getchar();
if (c == EOF)
break;
putchar(c);
}
if (c == EOF)
break;
if (name[0] == 'I' && name[1] == 'E' && name[2] == 'N' && name[3] == 'D')
{
/* should not happen */
break;
}
}
}