Re: [amsat-bb] D-block utility

[Gilbert Mackall <gilbert@xxxxxxxxxxxxxxxxxx>]

I think I posted this before, but here is a routine the allows you to 
decode D-blocks.  Feel free to use it...




Standard Disclaimer:  I want to be a programmer when I grow up;  I am 
not yet grown.


-------------------------------------------------------------------------------------------------------------------------

#include <math.h>
#include <stdio.h>
#include<stat.h>
#include <string.h>
#include <ctype.h>
#include <time.h>

struct dblock {
					char				ID[5];
					short				NB;		// NB=Number of blocks
					short				NS;		// NS sequence number
					short				N;		// N = number of bytes in block
				};
				
// This routine is passed a telmetry block,
// it is assumed the input routine has already done a CRC check.

void d_decode(unsigned char block[])
{



	time_t lclTime;
	struct tm *now;
	char ts[256]; /* time string */
	extern struct Pref_conf Pref;			
	unsigned short				x,i;
	unsigned char		Dblock[500];
	char				temp[255];
	FILE				*fp6,*fp7;
	
	struct dblock bIndex;
					
	// get time UTC
	lclTime = time(NULL);
	now = gmtime(&lclTime);
  			
	// setup directories
	strftime(ts, 256, ":TLM Folder:%Y", now);		
	mkdir(ts,0);
	strftime(ts, 256, ":TLM Folder:%Y:%b", now);		
	mkdir(ts,0);
	strftime(ts, 256, ":TLM Folder:%Y:%b:%d", now);		
	mkdir(ts,0);
	strftime(ts, 256, ":TLM Folder:%Y:%b:%d:", now);
  			
	// pull fileID from telemetry block	
	bIndex.ID[0]=block[2];
	bIndex.ID[1]=block[3];
	bIndex.ID[2]='\0';
			
	sprintf(temp,"%sd.%s.raw",ts,bIndex.ID);
	fp6=fopen(temp,"a+b");
	
	sprintf(temp,"%sd.%s.index",ts,bIndex.ID);
	fp7=fopen(temp,"ab");
	
	// pull the other header information from the block.		
	bIndex.NB = (block[5] << 8) + (0x00ff & block[4]);
	bIndex.NS = (block[7] << 8) + (0x00ff & block[6]);
	bIndex.N = (block[509] << 8) + (0x00ff & block[508]);
	
	//sprintf(temp,"\rFileID = %s ,   NS= %d",bIndex.ID,bIndex.NB);	// debug	
	//TlmDraw(temp);	
		
	sprintf(temp,"\rSN= %d ,  N= %d\r",bIndex.NS,bIndex.N);		// debug	
	TlmDraw(temp);	
			

			
	for(x=8,i=0;i<bIndex.N;x++,i++){
			if(!Pref.exor){    // If the D block has not already been XORed
				Dblock[i]=(unsigned char)(x ^ block[x]);
				}else{
				Dblock[i]=block[x]; // If we are reading from 
archived D block that has been XORed
				}		
			}	
		
		// seek offset NS*500
		fseek(fp6,(bIndex.NS*500),0);
		
		// write block N in length
		fwrite(Dblock,1,bIndex.N,fp6);
		fclose(fp6);
		
		// update index
		fwrite(&bIndex,1,sizeof(struct dblock ),fp7);
		fclose(fp7);
		

}


// Routine that tracks percent of file received

void	checkIndex(void)
{
	
	SFTypeList			typeList={'TEXT','????',0,0};
	StandardFileReply 	reply;
	short				fileRefNum;
	struct dblock 	bIndex;
	unsigned char 	i=0,j;
	float			x=0;
	long			c;
	char			temp[255];//t[11];
	unsigned short 	NSarray[4096]; // Support 2MB filesize. Note the 
spec allows for files with upto 32MB in length.			
		
	c=sizeof(struct dblock);	
	
	StandardGetFile(nil,0,typeList,&reply);
	
	if(reply.sfGood == 0)
		{
		
			return;
		}	
		
	FSpOpenDF(&reply.sfFile,fsRdPerm,&fileRefNum);  // use file 
selection dialog
		while ( !(FSRead(fileRefNum,&c,&bIndex)) )  // read in index.
		{
			NSarray[bIndex.NS]=12340; 	// mark this sequence
			
			//sprintf(temp,"\r%s NS=%d",bIndex.ID,bIndex.NS);	// debug	
			//TlmDraw(temp);								
		}
	FSClose(fileRefNum);
	
	// Count how many blocks we have
	for(i=0,j=0;i<bIndex.NB;i++){
		if(NSarray[i] == 12340){
				j++;}
		}
	
	x=(float)j/bIndex.NB; // what percentae of "D" blocks have been 
captured
	
	sprintf(temp,"\r%s NB=%d x=%2.2f \r",bIndex.ID,bIndex.NB,x);	// debug	
			TlmDraw(temp);
			
}










Gilbert Mackall
N3RZN

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org