/*
 * DMLib
 * -- Simple bitstream I/O functions
 * Programmed and designed by Matti 'ccr' Hamalainen
 * (C) Copyright 2012 Tecnic Software productions (TNSP)
 */
#include "dmbstr.h"


static BOOL dmPutByteFILE(DMBitStreamContext *ctx, const Uint8 val)
{
    return fputc(val, (FILE *) ctx->fp) == val;
}


void dmInitBitStreamContext(DMBitStreamContext *ctx)
{
    ctx->outBuf       = 0;
    ctx->outByteCount = 0;
    ctx->outBitCount  = 8;
}


int dmInitBitStreamFILE(DMBitStreamContext *ctx, FILE *fp)
{
    if (ctx == NULL || fp == NULL)
        return DMERR_NULLPTR;

    ctx->putByte = dmPutByteFILE;
    ctx->fp      = (void *) fp;

    dmInitBitStreamContext(ctx);

    return DMERR_OK;
}


BOOL dmPutBits(DMBitStreamContext *ctx, const int val, const int n)
{
    int i;
    unsigned int mask = 1 << (n - 1);

    for (i = 0; i < n; i++)
    {
        ctx->outBuf <<= 1;

        if (val & mask)
          ctx->outBuf |= 1;

        mask >>= 1;
        ctx->outBitCount--;

        if (ctx->outBitCount == 0)
        {
            if (!ctx->putByte(ctx, ctx->outBuf & 0xff))
                return FALSE;

            ctx->outBitCount = 8;
            ctx->outByteCount++;
        }
    }

    return TRUE;
}


int dmFlushBitStream(DMBitStreamContext *ctx)
{
  if (ctx == NULL)
      return DMERR_NULLPTR;

  if (ctx->outBitCount != 8)
      dmPutBits(ctx, 0, ctx->outBitCount);
  
  return 0;
}