I have some C code which performs varbyte compression on ints. I have inline'd this code, and wish to manage the output and input with some perl. I know that the varbyte works in other contexts, but when i compare the length of the output to the length of the input, I guess that something is clearly wrong. I have no experience with binary data in perl, i just assumed that if i didnt touch it, it'd remain as is. here is the C which i know works properly in other contexts:

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct vbyte_record{
   unsigned char* vbyte_result;
   short vbyte_len;
} oneRecord;

void displayBits(unsigned char*, int);
oneRecord vbyte_compress(int);

/*display bits of an unsigned char value*/
void displayBits(unsigned char* value, int len){
  int shift = 7;
  unsigned char mask = '1' << shift;
  unsigned i, j;
  for(j=0; j<len; j++){
     for(i=1; i<=8; i++){
        printf("%c", value[j] & mask ? '1': '0');
        value[j] <<= 1;
     }
  }
  return;
}

/* compress an integer into vbyte;
   first check how many bytes this integer needs;
   then set the highest bit of all byte to 1 except the lowest byte;
   encode each byte respectively
*/
oneRecord vbyte_compress(int number){
   short index = (short) floor(log10(number)/log10(128)); //number of 
+bytes needed
   unsigned char* result;
   short i;
   int remainder = number;
   div_t temp;
   unsigned char mask = (char) 1 << 7; //used to set highest bit to 1
   oneRecord record;

   result = (unsigned char*) malloc(sizeof(char)*(index+1));
   /* if there are more than one byte; encode the higher byte */
   if(index > 0){
     for(i=index; i>=1; i--){
        temp = div(remainder, (int)pow(128, i));
        result[index-i] = (char) temp.quot | mask;
        remainder = temp.rem;
     }
   }
   /*encode the lowest byte*/
   result[index] = (char) remainder;
   record.vbyte_result = result;
   record.vbyte_len = index+1;
   return record;
}


char* varbyte(int number)
{
   oneRecord record;
   int decom_num;

   record = vbyte_compress(number);

   return record.vbyte_result;
}
[download]

this line in my perl gives surprising results:

$compressed.= varbyte($x);
print "$x: ",length($x)," compressed ",length($compressed), "\n";
[download]

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