module NHC.Binary
  ( compareBin
  ) where

import NHC.GreenCard
import BinPtr
import BinHandle

%-#include "cLowBinary.h"
%-#include <stdlib.h>
    -- %-#include <stdio.h>
 
%dis ordering x = <fromEnum/toEnum> (int x)

%-#define LT 0
%-#define EQ 1
%-#define GT 2

%fun compareBin :: Int -> Int -> BinHandle -> BinPtr -> BinHandle -> BinPtr -> Ordering
%call (int sizex) (int sizey) (binHandle bhx) (binPtr x) (binHandle bhy) (binPtr y)
%code
%  /* size of x and y are not necessarily byte-aligned */
%  /* but bits of x and y are guaranteed byte-aligned at both ends */
%  int bytex = (sizex%8 ? (sizex/8)+1 : sizex/8);
%  int bytey = (sizey%8 ? (sizey/8)+1 : sizey/8);
%  int xptr, yptr;
%  if ((bhx->mode != RO) || (bhy->mode != RO)) {
%    fprintf(stderr,"Binary.compareBin: BinHandle is not Read-Only.");
%    exit(1);
%  }
%  xptr = (x - forceCacheTo(bhx,x)) / 8;
%  yptr = (y - forceCacheTo(bhy,y)) / 8;
%  /* fprintf(stderr,"compareBin: sizex=%d sizey=%d xoffset=%d yoffset=%d\n",
%                  sizex,sizey,x,y); */
%  retval = EQ;
%  while (bytex-- && bytey--) {
%    if (bhx->cache[xptr] != bhy->cache[yptr]) {
%      if (bhx->cache[xptr] < bhy->cache[yptr]) {
%        retval = LT;
%      } else {
%        retval = GT;
%      }
%      break;
%    }
%    xptr++; yptr++;
%    if (xptr==CACHESIZE) nextcache(bhx);
%    if (yptr==CACHESIZE) nextcache(bhy);
%  }
%result (ordering retval)