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

/* http://cpansearch.perl.org/src/SHLOMIF/Digest-JHash-0.10/JHash.xs */ 
/* overly documented version of fix, unsigned char* p ; */ 

/* Jenkins Hash http://burtleburtle.net/bob/hash/doobs.html */

typedef  unsigned long  int  U32tf;   /* unsigned 4-byte quantities */


void c_out0 ( char* str, U32tf a, U32tf b, U32tf c ) {
printf( "%-20s%16u  %016x - %16u  %016x - %16u  %016x \n", str,a,a,b,b,c,c );
} 

const int DEBUGODV = 1;

/* Need to constrain U32 to only 32 bits on 64 bit systems
 * For efficiency we only use the & 0xffffffff if required
 */

#if BYTEORDER > 0x4321 || defined(TRUNCATE_U32)
#define MIXODV(a,b,c) \
{ \
c_out0("  cm064         : ABC : ",a,b,c); \
  a &= 0xffffffff; b &= 0xffffffff; c &= 0xffffffff; \
c_out0("  cm &ff        : ABC : ",a,b,c); \
  a -= b;\
c_out0("  cm a1-b       : ABC : ",a,b,c); \
          a -= c; \
c_out0("  cm a1-c       : ABC : ",a,b,c); \
                  a ^= (c>>13);\
c_out0("  cm c1-x c>13  : ABC : ",a,b,c); \
 a &= 0xffffffff; \
c_out0("  cm a1         : ABC : ",a,b,c); \
\
\
  b -= c; b -= a; b ^= (a<<8);  b &= 0xffffffff; \
c_out0("  cm b1         : ABC : ",a,b,c); \
\
  c -= a; \
c_out0("  cm c1-a       : ABC : ",a,b,c); \
          c -= b; \
c_out0("  cm c1-b       : ABC : ",a,b,c); \
                  c ^= (b>>13);\
c_out0("  cm c1-x b>13  : ABC : ",a,b,c); \
                                c &= 0xffffffff; \
c_out0("  cm c1         : ABC : ",a,b,c); \
\
\
\
  a -= b; a -= c; a ^= (c>>12); a &= 0xffffffff; \
c_out0("  cm a2         : ABC : ",a,b,c); \
  b -= c; b -= a; b ^= (a<<16); b &= 0xffffffff; \
c_out0("  cm b2         : ABC : ",a,b,c); \
  c -= a; c -= b; c ^= (b>>5);  c &= 0xffffffff; \
c_out0("  cm c2         : ABC : ",a,b,c); \
  a -= b; a -= c; a ^= (c>>3);  a &= 0xffffffff; \
c_out0("  cm a3         : ABC : ",a,b,c); \
  b -= c; b -= a; b ^= (a<<10); b &= 0xffffffff; \
c_out0("  cm b3         : ABC : ",a,b,c); \
  c -= a; c -= b; c ^= (b>>15); c &= 0xffffffff; \
c_out0("  cm c3         : ABC : ",a,b,c); \
}
#else
#define MIXODV(a,b,c) \
{ \
c_out0(" cm032          : ABC : ",a,b,c); \
  a -= b; a -= c; a ^= (c>>13); \
  b -= c; b -= a; b ^= (a<<8);  \
  c -= a; c -= b; c ^= (b>>13); \
  a -= b; a -= c; a ^= (c>>12); \
  b -= c; b -= a; b ^= (a<<16); \
  c -= a; c -= b; c ^= (b>>5);  \
  a -= b; a -= c; a ^= (c>>3);  \
  b -= c; b -= a; b ^= (a<<10); \
  c -= a; c -= b; c ^= (b>>15); \
}
#endif

U32 jhashu( SV* str ) 
{
    STRLEN rawlen;
    unsigned char* p;
    U32tf a, b, c, len, length;
    U32tf x, y, z;


    /* extract the string data and string length from the perl scalar */
    p = (char*)SvPV(str, rawlen);
    length = len = (U32tf)rawlen;

    /* Test for undef or null string case and return 0 */
    if ( length == 0 ) {
        DEBUGODV && printf( "Recieved a null or undef string!\n" );
      return 0;
    }

    DEBUGODV && printf( "Received string %6i '%.*s'.\n", (int)len,(int)len, p );

    a = b = 0x9e3779b9;        /* golden ratio suggested by Jenkins */
    c = 0;
c_out0(" centry         : ABC : ",a,b,c); 
    while (len >= 12)
    {
        a += (p[0] + (((U32tf)p[1])<<8) + (((U32tf)p[2])<<16) +
              (((U32tf)p[3])<<24));
        b += (p[4] + (((U32tf)p[5])<<8) + (((U32tf)p[6])<<16) +
              (((U32tf)p[7])<<24));
        c += (p[8] + (((U32tf)p[9])<<8) + (((U32tf)p[10])<<16) +
              (((U32tf)p[11])<<24));
c_out0(" cloop+        : ABC : ",a,b,c); 
        MIXODV(a, b, c);
c_out0(" clout         : ABC : ",a,b,c); 
        p += 12;
        len -= 12;
    }
    x = y = z= 0; 
    z += length;
    switch(len) {
    case 11: z+=((U32tf)p[10]<<24);
    case 10: z+=((U32tf)p[9]<<16);
    case 9:  z+=((U32tf)p[8]<<8);
    case 8:  y+=((U32tf)p[7]<<24);
    case 7:  y+=((U32tf)p[6]<<16);
    case 6:  y+=((U32tf)p[5]<<8);
    case 5:  y+=((U32tf)p[4]);
    case 4:  x+=((U32tf)p[3]<<24);
    case 3:  x+=((U32tf)p[2]<<16);
    case 2:  x+=((U32tf)p[1]<<8);
    case 1:  x+=((U32tf)p[0]);
    }
c_out0(" cpost8         : XYZ : ",x,y,z); 
a+=x; b+=y;c+=z; 
c_out0(" cpost+         : ABC : ",a,b,c); 
    MIXODV(a, b, c);
c_out0(" cpout          : ABC : ",a,b,c); 
    DEBUGODV && printf( "Hash value is %d.\n", (int)(c) );

    return(c);
}