Update this shit.

pngread.c

@@ -0,0 +1,178 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <zlib.h>
+
+uint32_t endianswap( uint32_t n )
+{
+	// if we're in a big endian system, we don't need this
+	uint16_t testme = 0x1234;
+	if ( *(uint8_t*)(&testme) == 0x12 ) return n;
+	uint32_t on;
+	for ( int i=0; i<4; i++ )
+		*(((uint8_t*)(&on))+i) = *(((uint8_t*)(&n))+(3-i));
+	return on;
+}
+
+typedef struct
+{
+	uint8_t highbitcheck;
+	char sig[3];
+	char crlf[2];
+	char dosstop;
+	char lf;
+} pnghead_t;
+
+typedef struct
+{
+	uint32_t length;
+	char type[4];
+	uint8_t *data;
+	uint32_t crc;
+} pngchunk_t;
+
+typedef struct
+{
+	uint32_t width, height;
+	uint8_t depth, type, compression, filter, interlace;
+} ihdr_t;
+
+typedef struct
+{
+	uint32_t xppu, yppu;
+	uint8_t unit;
+} phys_t;
+
+int exitval = 0;
+FILE *f = 0;
+int nchunk = 0;
+pnghead_t hdr = {0,0,0,0,0};
+pngchunk_t chk = {0,0,0,0};	// make sure this is null at the very start
+uint32_t curcrc = 0;
+int validcrc = 0;
+uint8_t *tdat = 0;	// accumulated data for all IDAT chunks
+uint32_t tdatsiz = 0;	// size of it
+
+void readIHDR( ihdr_t* ihdr )
+{
+	printf(" width: %u\n height: %u\n depth: %u\n type: %u\n compression: %u\n filter: %u\n interlace: %u\n",
+		endianswap(ihdr->width),endianswap(ihdr->height),ihdr->depth,ihdr->type,ihdr->compression,ihdr->filter,ihdr->interlace);
+}
+
+// read up a stream chunk
+void readIDAT( uint8_t* dat, uint32_t len )
+{
+	if ( tdat ) tdat = realloc(tdat,tdatsiz+len);
+	else tdat = malloc(len);
+	memcpy(tdat+tdatsiz,dat,len);
+	tdatsiz += len;
+}
+
+// process the whole thing
+void processIDAT( void )
+{
+}
+
+void readpHYs( phys_t* phys )
+{
+	printf(" xppu: %u\n yppu: %u\n unit: %u\n",endianswap(phys->xppu),endianswap(phys->yppu),phys->unit);
+}
+
+void readtEXt( uint8_t* data, uint32_t len )
+{
+	uint8_t *key = data;
+	uint8_t *val = data+strlen(data)+1;
+	uint32_t vallen = len-(val-key);
+	printf(" '%s' :: '%.*s'\n",key,vallen,val);
+}
+
+void readchunkdata( pngchunk_t* chk )
+{
+	if ( !strncmp(chk->type,"IHDR",4) )
+		readIHDR((ihdr_t*)chk->data);
+	else if ( !strncmp(chk->type,"pHYs",4) )
+		readpHYs((phys_t*)chk->data);
+	else if ( !strncmp(chk->type,"tEXt",4) )
+		readtEXt(chk->data,chk->length);
+}
+
+
+int main( int argc, char **argv )
+{
+	if ( argc < 2 )
+	{
+		printf("No file supplied.\n");
+		exitval = 0;
+		goto endmii;
+	}
+	f = fopen(argv[1],"rb");
+	if ( !f )
+	{
+		printf("Failed to open file.\n");
+		exitval = 1;
+		goto endmii;
+	}
+	fread(&hdr,1,sizeof(hdr),f);
+	if ( hdr.highbitcheck != 0x89 )
+	{
+		printf("High bit check failed.\n");
+		exitval = 2;
+		goto endmii;
+	}
+	if ( strncmp(hdr.sig,"PNG",3) )
+	{
+		printf("PNG signature check failed.\n");
+		exitval = 4;
+		goto endmii;
+	}
+	if ( strncmp(hdr.crlf,"\r\n",2) )
+	{
+		printf("CRLF check failed.\n");
+		exitval = 8;
+		goto endmii;
+	}
+	if ( hdr.dosstop != '\032' )
+	{
+		printf("EOF check failed.\n");
+		exitval = 16;
+		goto endmii;
+	}
+	if ( hdr.lf != '\n' )
+	{
+		printf("LF check failed.\n");
+		exitval = 32;
+		goto endmii;
+	}
+readchunk:
+	fread(&chk,1,8,f);	// read size and type first
+	chk.length = endianswap(chk.length);	// swap from BE
+	if ( (nchunk == 0) && strncmp(chk.type,"IHDR",4) )
+	{
+		printf("First chunk is not IHDR.\n");
+		exitval = 64;
+		goto endmii;
+	}
+	// (re)allocate data
+	if ( chk.data ) chk.data = realloc(chk.data,chk.length);
+	else chk.data = malloc(chk.length);
+	fread(chk.data,1,chk.length,f);	// read data
+	fread(&(chk.crc),1,4,f);	// read CRC
+	chk.crc = endianswap(chk.crc);
+	curcrc = crc32(0,chk.type,4);
+	if ( chk.length ) curcrc = crc32(curcrc,chk.data,chk.length);
+	validcrc = (curcrc == chk.crc);
+	printf("%.4s chunk of length %u (CRC32: %08X, %s).\n",chk.type,chk.length,chk.crc,validcrc?"OK":"FAILED");
+	if ( !validcrc ) printf("  CRC32 ACTUAL: %08X\n",curcrc);
+	else readchunkdata(&chk);
+	nchunk++;
+	if ( strncmp(chk.type,"IEND",4) ) goto readchunk;
+	long cpos = ftell(f);
+	fseek(f,0,SEEK_END);
+	long epos = ftell(f);
+	if ( epos > cpos ) printf("%lu bytes of extra data after IEND.\n",epos-cpos);
+endmii:
+	if ( f ) fclose(f);
+	if ( chk.data ) free(chk.data);
+	return exitval;
+}