text: /* ----------------------------------------------------------------------- *
   *
   *   Copyright 2009 Pierre-Alexandre Meyer
   *
   *   Some parts borrowed from chain.c32:
   *
   *   Copyright 2003-2009 H. Peter Anvin - All Rights Reserved
   *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
   *
   *   This file is part of Syslinux, and is made available under
   *   the terms of the GNU General Public License version 2.
   *
   * ----------------------------------------------------------------------- */
  
  #include <com32.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include <disk/common.h>
  #include <disk/errno_disk.h>
  #include <disk/read.h>
  #include <disk/util.h>
  #include <disk/write.h>
  
  /**
   * write_sectors - write several sectors from disk
   * @drive_info:		driveinfo struct describing the disk
   * @lba:		Position to write
   * @data:		Buffer to write
   * @size:		Size of the buffer (number of sectors)
   *
   * Return the number of sectors write on success or -1 on failure.
   * errno_disk contains the error number.
   **/
  int write_sectors(const struct driveinfo *drive_info, const unsigned int lba,
  		  const void *data, const int size)
  {
      com32sys_t inreg, outreg;
      struct ebios_dapa *dapa;
      void *buf;
      int rv = -1;
  
      buf = lmalloc(size);
      if (!buf)
  	return -1;
  
      dapa = lmalloc(sizeof(*dapa));
      if (!dapa)
  	goto out;
  
      memcpy(buf, data, size);
      memset(&inreg, 0, sizeof inreg);
  
      if (drive_info->ebios) {
  	dapa->len = sizeof(*dapa);
  	dapa->count = size;
  	dapa->off = OFFS(buf);
  	dapa->seg = SEG(buf);
  	dapa->lba = lba;
  
  	inreg.esi.w[0] = OFFS(dapa);
  	inreg.ds = SEG(dapa);
  	inreg.edx.b[0] = drive_info->disk;
  	inreg.eax.w[0] = 0x4300;	/* Extended write */
      } else {
  	unsigned int c, h, s;
  
  	if (!drive_info->cbios) {	// XXX errno
  	    /* We failed to get the geometry */
  	    if (lba)
  		goto out;	/* Can only write MBR */
  
  	    s = 1;
  	    h = 0;
  	    c = 0;
  	} else
  	    lba_to_chs(drive_info, lba, &s, &h, &c);
  
  	// XXX errno
  	if (s > 63 || h > 256 || c > 1023)
  	    goto out;
  
  	inreg.eax.w[0] = 0x0301;	/* Write one sector */
  	inreg.ecx.b[1] = c & 0xff;
  	inreg.ecx.b[0] = s + (c >> 6);
  	inreg.edx.b[1] = h;
  	inreg.edx.b[0] = drive_info->disk;
  	inreg.ebx.w[0] = OFFS(buf);
  	inreg.es = SEG(buf);
      }
  
      /* Perform the write */
      if (int13_retry(&inreg, &outreg)) {
  	errno_disk = outreg.eax.b[1];	/* Give up */
      } else
  	rv = size;
  out:
      lfree(dapa);
      lfree(buf);
      return rv;
  }
  
  /**
   * write_verify_sectors - write several sectors from disk
   * @drive_info:		driveinfo struct describing the disk
   * @lba:		Position to write
   * @data:		Buffer to write
   **/
  int write_verify_sector(struct driveinfo *drive_info,
  			const unsigned int lba, const void *data)
  {
      return write_verify_sectors(drive_info, lba, data, SECTOR);
  }
  
  /**
   * write_verify_sectors - write several sectors from disk
   * @drive_info:		driveinfo struct describing the disk
   * @lba:		Position to write
   * @data:		Buffer to write
   * @size:		Size of the buffer (number of sectors)
   **/
  int write_verify_sectors(struct driveinfo *drive_info,
  			 const unsigned int lba,
  			 const void *data, const int size)
  {
      char *rb = malloc(SECTOR * size * sizeof(char));
      int status;
  
      if (write_sectors(drive_info, lba, data, size) == -1)
  	return -1;		/* Write failure */
  
      if (read_sectors(drive_info, rb, lba, size) == -1)
  	return -1;		/* Readback failure */
  
      status = memcmp(data, rb, SECTOR * size);
      free(rb);
      return status ? -1 : 0;
  }
  