From fda048987789cf1bcf067115a593042af5ade502 Mon Sep 17 00:00:00 2001
From: Alan Kennedy <kennedya@3dgames.com.ar>
Date: Wed, 23 Jun 2004 08:28:26 +0000
Subject: [PATCH 1/1] Listo en teoria Huffman Compresor/Descompresor ByFile y
 Bychunk. Maniana detallo un poco el API y si tengo pilas ahora lo acoplo en
 JACU, sino tomorrow porque no doy mas. Vamo que llegamos al viernes..

---
 src/statichuff/main_bychunk.c | 21 +++++++++++++++----
 src/statichuff/statichuff.c   | 39 ++++++++++++++++++++++++++++++++---
 src/statichuff/statichuff.h   |  4 +++-
 3 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/src/statichuff/main_bychunk.c b/src/statichuff/main_bychunk.c
index eafe694..43426e8 100644
--- a/src/statichuff/main_bychunk.c
+++ b/src/statichuff/main_bychunk.c
@@ -11,7 +11,7 @@ int main(int argc, char* argv[])
 	int dflag = 0;
 	int tflag = 0;
 	long int volumesize = 0;
-	int lastchunk,i,j,ch;
+	int lastchunk,i,j,ch,decoded = 0;
 			
 	while ((ch = getopt(argc, argv, "cdt:")) != -1) { 
 		 
@@ -58,7 +58,7 @@ int main(int argc, char* argv[])
 		/* Le indico al huffman que efectivamente comprima los chunks */
 		shuff_encode_file(shuff);
 		
-		/* De init shuffman by chunks */
+		/* De init encoder */
 		shuff_deinit_encoder(shuff);
 		
 		/* Free mem allocated by main */
@@ -70,8 +70,21 @@ int main(int argc, char* argv[])
 	}
 	
 	if (dflag == 1) { 
-		/* Descomprimo */
-		/*return shuff_decode_file(argv[optind],argv[optind+1]);*/		
+		/* Init decoder */
+		shuff = shuff_init_decoder(argv[optind],NULL);
+		fp = fopen("chunkdump.txt","w");
+		
+		/* Gimme chunks till last one */
+		while (shuff_decode_chunk(shuff,chunk,4,&decoded))
+			fwrite(chunk,decoded,1,fp);
+		
+		/* Last chunk written alone */
+		fwrite(chunk,decoded,1,fp);
+		fclose(fp);
+		
+		/* Deinit decoder */
+		shuff_deinit_decoder(shuff);
+		free(shuff);
 	}
 		
 	return 0;
diff --git a/src/statichuff/statichuff.c b/src/statichuff/statichuff.c
index a2f6265..908729b 100644
--- a/src/statichuff/statichuff.c
+++ b/src/statichuff/statichuff.c
@@ -308,6 +308,36 @@ SHUFFNODE *shuff_decode_symbols(SHUFFNODE *entrynode, unsigned long int buffer,
 	else return shuff_decode_symbols(entrynode->rchild,buffer,bitsleft,symbol);
 }
 
+int shuff_decode_chunk(HUFF_STATE *shuff, char *chunk, int chunksize, int *decodedbytes)
+{
+	SHUFFNODE *currnode = shuff->codetree;	
+	unsigned short int decoded_symbol;	
+	*decodedbytes = 0;
+	
+	while (!vfeof(shuff->decoderfp) && (shuff->bytesleft > 0) && (*decodedbytes < chunksize)) {
+		
+		/* Leo un buffer de 32 bits si es que quedo vacio el anterior */
+		if (shuff->bitsleft == 0) {
+			if (vfread(&(shuff->codebuffer),sizeof(unsigned long int),1,shuff->decoderfp) != 1) continue;
+			shuff->bitsleft = sizeof(unsigned long int) * 8;
+		}
+		
+		/* Proceso el buffer sacando simbolos till se me agote el buffer, file o chunk */
+		while ((shuff->bitsleft > 0) && (shuff->bytesleft > 0) && (*decodedbytes < chunksize)) {	
+			currnode = shuff_decode_symbols(currnode,shuff->codebuffer,&(shuff->bitsleft),&decoded_symbol);
+			/* Si obtuve un symbolo valido lo emito*/
+			if (decoded_symbol != 256) {				
+				chunk[(*decodedbytes)++] = decoded_symbol;
+				currnode = shuff->codetree;				
+				--(shuff->bytesleft);
+			}						
+		}		
+	}
+	
+	if (shuff->bytesleft == 0) return 0;
+	else return 1;
+}
+
 int shuff_decode_file(HUFF_STATE *shuff)
 {	
 	SHUFFNODE *currnode;	
@@ -316,7 +346,7 @@ int shuff_decode_file(HUFF_STATE *shuff)
 	unsigned short int decoded_symbol;
 	int bitsleft;	
 	
-	/* Levanto cuantos bytes decodeo y la freq table */	
+	/* Comienzo a decodificar, pues la tabla ya la levante en el decinit */
 	if ((fpdest = fopen(shuff->targetfile,"w")) == NULL) return 0;	
 	currnode = shuff->codetree;
 	
@@ -338,6 +368,7 @@ int shuff_decode_file(HUFF_STATE *shuff)
 		}		
 	}
 			
+	/* Close destination */
 	fclose(fpdest);	
 	
 	return 1;
@@ -350,6 +381,8 @@ HUFF_STATE *shuff_init_decoder(char *inputfile, char *outputfile)
 	shuff->freqtable = (t_freq*)malloc(sizeof(t_freq)*256);	
 	
 	/* Init fields */
+	shuff->codebuffer = 0;
+	shuff->bitsleft = 0;
 	shuff->coderfp = NULL;
 	shuff->targetfile = NULL;
 	shuff->sourcefile = (char*)malloc(sizeof(char)*(strlen(inputfile)+1));
@@ -425,8 +458,8 @@ void shuff_deinit_encoder(HUFF_STATE *shuff)
 	free(shuff->freqtable);	
 	if (shuff->coderfp != NULL) fclose(shuff->coderfp);
 	if (shuff->preloadfreq == 1) unlink(shuff->sourcefile);
-	free(shuff->sourcefile);
-	free(shuff->targetfile);			
+	if (shuff->targetfile != NULL) free(shuff->targetfile);			
+	free(shuff->sourcefile);	
 	
 	/* Destruyo recursivamente el arbol de codigos */
 }
diff --git a/src/statichuff/statichuff.h b/src/statichuff/statichuff.h
index d892aea..35a550c 100644
--- a/src/statichuff/statichuff.h
+++ b/src/statichuff/statichuff.h
@@ -30,7 +30,9 @@ typedef struct t_huff {
 	t_freq *freqtable; /* Tabla de frecuencias */
 	t_freq sumfreq; /* Frecuencia total acumulada */
 	SHUFFNODE *codetree; /* Puntero al arbol de codigos prefijos */		
-	unsigned long int bytesleft; /* cuanto falta descomprimir en un bychunk */	
+	unsigned long int bytesleft; /* Cuanto falta descomprimir en un bychunk */	
+	unsigned long int codebuffer; /* Buffer de descompresion para bychunk */
+	int bitsleft; /* Posicion en el buffer de descompresion para bychunk */
 } HUFF_STATE;
 
 
-- 
2.43.0