Porformance problem building a list
Hi, i regret asking for help on my very first topic on the forum, but i truly need a hand or two, and please forgive my poor english.
I have to read "symbols" from a file, and build a list saving on each node a symbol and the number of times that symbol appears, it may seem easy, but the problem is that the program has to finish under 3 seconds and there are 26 million characters to be read. As you will see, im a novice, so my code is very rudimentary, and of course its not even close to those 3 seconds i need to get.
You may be wondering why i wrote "symbols", the reason is that i get from the parameter line how many ASCII characters form a "symbol" for example if i get "2" from the parameter line, each symbol will be pairs of ASCIIs like "7(" or "P;".
That being said, i googled a lot with no succes, so i hope that you guys can help me figure out the way to speed up this program. Thanks a lot for your time.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
int num_param, t;
char *param[4];
struct symbolic_node{
int counter;
short status;
struct symbolic_node *sig;
struct symbolic_node *ant;
char *symb;
};
int sintax_check();
int symbol_obtainer(char **);
void list_builder(char **,int,struct symbolic_node **);
int main(int argc, char *argv[]){
int i,j,sintax_error,n;
short array_pos=0;
FILE *pFile;
int lSize;
char *buffer;
struct symbolic_node *l_symb;
num_param=argc-1;
for(i=1;i<=num_param;i++){
param[i]=argv[i];
}
n=atoi(param[2]);
sintax_error=sintax_check();
if(sintax_error==1){
fputs("Sintax error\n",stderr);
}else{
lSize=symbol_obtainer(&buffer);
list_builder(&buffer,lSize,&l_symb);
free(buffer);
printf("Done\n");
}
}
int sintax_check(){
int i, error=0;
char *ptr;
if(num_param!=2){
error=1;
}else{
if(error==0){
if(isdigit(param[2][0])==0)error=1;
}
}
return error;
}
int symbol_obtainer(char **buff){
FILE *pfile;
int i,res_reading, n;
int num_bytes;
char *char_storage;
n=atoi(param[2]);
pfile=fopen(param[1],"rb");
if(pfile==NULL){
fputs("File not found\n",stderr);
exit(1);
}else{
fseek(pfile,0,SEEK_END);
num_bytes=ftell(pfile);
rewind(pfile);
num_bytes=num_bytes/n;
char_storage=(char *)calloc(num_bytes,n);
if(char_storage==NULL){
fputs("Memory allocation error\n",stderr);
exit(2);
}
res_reading=fread(char_storage,n,num_bytes,pfile);
if(res_reading!=num_bytes){
fputs("Reading error\n",stderr);
exit(3);
}
}
*buff=char_storage;
fclose(pfile);
return num_bytes;
}
void list_builder(char **buff,int tamanio,struct symbolic_node **header){
struct symbolic_node *aux, *aux1, *aux2, *aux3, *lsymb;
short n,run_level;
short num_nodos=0;
int i,cont=0;
char *char_storage;
n=atoi(param[2]);
aux=(struct symbolic_node *)malloc(sizeof(struct symbolic_node));
aux->ant=NULL;
aux->sig=NULL;
char_storage=*buff;
*header=aux;
aux3=aux;
aux->symb=(char *)malloc(n);
memcpy(aux->symb,char_storage,n);
aux->counter=1;
num_nodos++;
char_storage+=n;
for(i=1;i<tamanio;i++){
run_level=0;
aux1=(struct symbolic_node *)malloc(sizeof(struct symbolic_node));
aux1->symb=(char*)malloc(n);
memcpy(aux1->symb,char_storage,n);
aux1->counter=1;
aux2=aux;
while(aux2!=NULL&&(run_level!=1)){
if(memcmp(aux2->symb,aux1->symb,n)==0){
free(aux1->symb);
free(aux1);
aux2->counter+=1;
run_level=1;
}
aux3=aux2;
aux2=aux2->sig;
}
if(run_level==0){
num_nodos++;
aux1->ant=aux3;
aux3->sig=aux1;
aux3=aux3->sig;
aux1->sig=NULL;
}
char_storage+=n;
}
}
Thx a lot, plz let me know if you dont understand something or if you need anything else.
