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Top Forums Shell Programming and Scripting Extract sequences of bytes from binary for differents blocks Post 302843978 by ahamed101 on Friday 16th of August 2013 02:14:41 AM
Old 08-16-2013
Code:
#include <stdio.h>
#include <stdlib.h>

#define err(x) {printf("\nError: %s... Exiting...\n", x); exit(1);}

static unsigned char pat1[] = {0x99, 0x11, 0x45, 0x27};
static unsigned char pat2[] = {0x73, 0x49};
static unsigned char pat3[] = {0xff, 0x34};
static unsigned char intrim_pat1[][2] = { {0x03, 0x80}, {0x03, 0x81}, {0x03, 0x83}, {0x03, 0x86}, {0x03, 0x87} };
static unsigned char end[] = {0xff, 0x33};

void print_data(const unsigned char *ptr, int len)
{
        int i;
        for(i=0;i<=len;i++)
                printf("%02x ", ptr[i]);
        printf("\n");
        return;
}

int main(int argc, char **argv)
{
        if(argc < 2)
                err("File name missing");

        char found = 0, more = 0;
        unsigned char buf[32];
        unsigned char *ptr = buf;
        int pos = 0, i;
        int arr_size = (sizeof(intrim_pat1)/2);

        FILE *fp = fopen(argv[1], "rb");
        if(!fp) err("Unable to open the file");

        while(2 == fread(ptr, sizeof(char), 2, fp)){
                pos = ftell(fp);

                //check for end of file pattern
                if(found && !memcmp(buf, end, 2)){
                        found=0; //start over or stop??
                        continue;
                }

                //check for 0xff 0x34
                if(found && !(memcmp(buf, pat3, 2))){
                        more = 1;
                        continue;
                }

                if(found && more){
                        for(i=0; i< arr_size; i++){
                                if(!memcmp(buf, intrim_pat1[i], 2)){
                                        if(15 != fread(ptr+2, sizeof(char), 15, fp))
                                                err("Insufficient data");
                                        print_data(ptr, 16);
                                        more=0;
                                        continue;// start with the next byte
                                }
                        }
                }

                if(buf[0] == 0x32){
                        if(18 != fread(ptr+2, sizeof(char), 18, fp))
                                err("Insufficient data");
                        if(memcmp(buf+4, pat1, 4) && memcmp(buf+12, pat2, 2)){
                                fseek(fp, pos, SEEK_SET);
                        }else{
                                found = 1; //found the starting of the block with data
                                print_data(ptr, 19);
                        }
                        continue;
                }
                pos--;
                if(fseek(fp, pos, SEEK_SET))
                        err("Error in seeking");
        }

        return 0;
}

--ahamed

Last edited by ahamed101; 08-16-2013 at 03:24 AM..
 

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SDL_AudioCVT(3) 						 SDL API Reference						   SDL_AudioCVT(3)

NAME
SDL_AudioCVT - Audio Conversion Structure STRUCTURE DEFINITION
typedef struct{ int needed; Uint16 src_format; Uint16 dest_format; double rate_incr; Uint8 *buf; int len; int len_cvt; int len_mult; double len_ratio; void (*filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); int filter_index; } SDL_AudioCVT; STRUCTURE DATA
needed Set to one if the conversion is possible src_format Audio format of the source dest_format Audio format of the destination rate_incr Rate conversion increment buf Audio buffer len Length of the original audio buffer in bytes len_cvt Length of converted audio buffer in bytes (calculated) len_mult buf must be len*len_mult bytes in size(calculated) len_ratio Final audio size is len*len_ratio filters[10](..) Pointers to functions needed for this conversion filter_index Current conversion function DESCRIPTION
The SDL_AudioCVT is used to convert audio data between different formats. A SDL_AudioCVT structure is created with the SDL_BuildAudioCVT function, while the actual conversion is done by the SDL_ConvertAudio function. Many of the fields in the SDL_AudioCVT structure should be considered private and their function will not be discussed here. Uint8 *buf int len int len_mult double len_ratio SEE ALSO
SDL_BuildAudioCVT, SDL_ConvertAudio, SDL_AudioSpec SDL
Tue 11 Sep 2001, 22:58 SDL_AudioCVT(3)
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