#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#define UCHAR unsigned char

UCHAR p_tbl[256] = {
  251,175,119,215, 81, 14, 79,191,103, 49,181,143,186,157,  0,232,
   31, 32, 55, 60,152, 58, 17,237,174, 70,160,144,220, 90, 57,223,
   59,  3, 18,140,111,166,203,196,134,243,124, 95,222,179,197, 65,
  180, 48, 36, 15,107, 46,233,130,165, 30,123,161,209, 23, 97, 16,
   40, 91,219, 61,100, 10,210,109,250,127, 22,138, 29,108,244, 67,
  207,  9,178,204, 74, 98,126,249,167,116, 34, 77,193,200,121,  5,
   20,113, 71, 35,128, 13,182, 94, 25,226,227,199, 75, 27, 41,245,
  230,224, 43,225,177, 26,155,150,212,142,218,115,241, 73, 88,105,
   39,114, 62,255,192,201,145,214,168,158,221,148,154,122, 12, 84,
   82,163, 44,139,228,236,205,242,217, 11,187,146,159, 64, 86,239,
  195, 42,106,198,118,112,184,172, 87,  2,173,117,176,229,247,253,
  137,185, 99,164,102,147, 45, 66,231, 52,141,211,194,206,246,238,
   56,110, 78,248, 63,240,189, 93, 92, 51, 53,183, 19,171, 72, 50,
   33,104,101, 69,  8,252, 83,120, 76,135, 85, 54,202,125,188,213,
   96,235,136,208,162,129,190,132,156, 38, 47,  1,  7,254, 24,  4,
  216,131, 89, 21, 28,133, 37,153,149, 80,170, 68,  6,169,234, 151
};

UCHAR
pearson(const UCHAR *message, size_t len)
{
    size_t pos  = len;
    UCHAR  hash = len;

    while (pos > 0) {
        hash = p_tbl[hash ^ message[--pos]];
    }

    return hash;
}

MODULE = Digest::Pearson		PACKAGE = Digest::Pearson		

unsigned char
pearson(msg)
        SV *msg
    PROTOTYPE: $
    PREINIT:
        STRLEN         len;
        unsigned char *octets;
    CODE:
        octets = SvPV(msg, len);
        RETVAL = pearson(octets, len);
    OUTPUT:
        RETVAL