/*******************************************************************************
* bmp1.c
*	Microsoft Windows bitmap (BMP) file functions.
*
* 1.0 01-27-92 drt.  First cut.
* 1.1 08-25-92 drt.  Renamed bmp_header members.
*
* Copyright (c)1992-94, David R. Tribble.
*/


/* includes */

#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "bmp.h"


/* public variables */

unsigned int		bmp_pow2[] =
{
      1,    2,    4,    8,   16,    32,    64, 128, 256,
    512, 1024, 2048, 4096, 8192, 16384, 32768U
};


/* private variables */

static unsigned short	h_id = BMP_HDR_MAGIC;


/*******************************************************************************
* bmp_open
*	Opens a BMP file for either reading, writing, or both.
*
* returns
*	Pointer to a malloc'd BMP_FILE struct referring to an newly opened
*	BMP file, or NULL on error.
*/

BMP_FILE * bmp_open(const char *name, int mode)
{
    int		err;
    BMP_FILE *	fp;
    char *	m;


    /* check args */
    if (name == NULL  ||  name[0] == '\0')
    {
        /* invalid file name */
        errno = EINVAL;
        return NULL;
    }

    /* check mode */
    if (mode & O_RDONLY)
        m = "rb";
    else if (mode & O_WRONLY)
        m = "wb";
    else if (mode & O_RDWR)
        m = "w+b";
    else
    {
        /* invalid mode */
        errno = EINVAL;
        return NULL;
    }

    /* allocate a file control struct */
    fp = malloc(sizeof(BMP_FILE));
    if (fp == NULL)
    {
        /* out of memory */
        errno = ENOMEM;
        return NULL;
    }
    memset(fp, 0, sizeof(*fp));

    /* open the file */
    fp->fp = fopen(name, m);
    err = errno;
    if (fp->fp == NULL)
    {
        /* can't open file */
        free(fp);
        errno = err;
        return NULL;
    }

    /* initialize file control info */
    fp->h.id =              h_id;
    fp->h.filesize =        0;
    fp->h.r[0] =            0;
    fp->h.r[1] =            0;
    fp->h.r[2] =            0;
    fp->h.r[3] =            0;
    fp->h.headersize =      0;
    fp->h.infoSize =        0;
    fp->h.width =           0;
    fp->h.depth =           0;
    fp->h.biPlanes =        0;
    fp->h.bits =            0;
    fp->h.biCompression =   BMP_CMP_NONE;
    fp->h.biSizeImage =     0;
    fp->h.biXPelsPerMeter = 0;
    fp->h.biYPelsPerMeter = 0;
    fp->h.biClrUsed =       0;
    fp->h.biClrImportant =  0;
    fp->map =               NULL;
    fp->mode =   mode;
    fp->flags =  0;
    fp->ncols =  0;
    fp->rep =    0;
    fp->pix =    0;
    fp->byteno = 0;
    fp->bitno =  0;
    fp->byte =   0;
    return fp;
}


/*******************************************************************************
* bmp_close
*	Close a previously opened BMP file.
*
* returns
*	Zero if successful, otherwise a errno.
*/

int bmp_close(BMP_FILE *fp)
{
    int		rc = 0;


    /* check args */
    if (fp == NULL)
    {
        /* invalid file pointer */
        errno = EINVAL;
        return NULL;
    }

    /* close file, if open */
    if (fp->fp != NULL)
        fclose(fp->fp);

    /* deallocate file control struct */
    fp->fp = NULL;
    free(fp);
    return rc;
}


/* end bmp1.c */