module NHC.Binary
  ( openBin
  ) where

import NHC.GreenCard
import BinHandle ({-type-}BinHandle(..))
import BinIOMode ({-type-}BinIOMode(..))
import BinLocation ({-type-}BinLocation(..), fromBinLocation)

%-#include "cLowBinary.h"
%-#include <fcntl.h>
%-#include <stdlib.h>

%fun openBin :: BinLocation -> IO BinHandle
%call (binLocation f fp m)
%code
%  bh = (BinHandle)malloc(sizeof(BinState));       /* assume unfailing */
%  bh->mode = m; 
%  bh->file = f;
%  bh->cptr = 0;
%  if (bh->file) {
%    switch (bh->mode) {
%      case RO:  bh->loc.fd = open(fp,O_RDONLY); break;		/* ditto */
%      case WO:  bh->loc.fd = open(fp,(O_WRONLY|O_CREAT|O_TRUNC),0644); break;
%      case RW:  bh->loc.fd = open(fp,(O_RDWR|O_CREAT),0644); break;
%      default:  exit(1);
%    }					/* permissions 0644=-rw-r--r-- */
%    bh->attrib.eof  = 0;
%    bh->adjust.vptr = 0;
%    switch (bh->mode) {
%      case WO:  bh->highwater = 0;
%                break;
%      default:  bh->highwater = 8 * lseek(bh->loc.fd,0,SEEK_END);
%                if (bh->highwater>0) {
%                  char c=0;
%                  lseek(bh->loc.fd,-1,SEEK_END);
%                  read(bh->loc.fd,&c,1);
%                  bh->highwater -= (int)c;
%                }
%                break;
%    }
%    lseek(bh->loc.fd,0,SEEK_SET);
%  } else {
%    NodePtr n = C_ALLOC(1+EXTRA);
%    n[0] = CONSTRW(0,EXTRA);
%    bh->loc.sp = stableInsert(n);
%    bh->attrib.size = 0;
%    bh->adjust.here = 0;
%    bh->highwater   = 0;
%  }
%  opencache(bh);
%result (binHandle bh)