src/core/iobuf.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <stdint.h>
  20 #include <gpxe/malloc.h>
  21 #include <gpxe/iobuf.h>
  22
  23 /** @file
  24  *
  25  * I/O buffers
  26  *
  27  */
  28
  29 /**
  30  * Allocate I/O buffer
  31  *
  32  * @v len       Required length of buffer
  33  * @ret iobuf   I/O buffer, or NULL if none available
  34  *
  35  * The I/O buffer will be physically aligned to a multiple of
  36  * @c IOBUF_SIZE.
  37  */
  38 struct io_buffer * alloc_iob ( size_t len ) {
  39         struct io_buffer *iobuf = NULL;
  40         void *data;
  41
  42         /* Pad to minimum length */
  43         if ( len < IOB_ZLEN )
  44                 len = IOB_ZLEN;
  45
  46         /* Align buffer length */
  47         len = ( len + __alignof__( *iobuf ) - 1 ) &
  48                 ~( __alignof__( *iobuf ) - 1 );
  49
  50         /* Allocate memory for buffer plus descriptor */
  51         data = malloc_dma ( len + sizeof ( *iobuf ), IOB_ALIGN );
  52         if ( ! data )
  53                 return NULL;
  54
  55         iobuf = ( struct io_buffer * ) ( data + len );
  56         iobuf->head = iobuf->data = iobuf->tail = data;
  57         iobuf->end = iobuf;
  58         return iobuf;
  59 }
  60
  61 /**
  62  * Free I/O buffer
  63  *
  64  * @v iobuf     I/O buffer
  65  */
  66 void free_iob ( struct io_buffer *iobuf ) {
  67         if ( iobuf ) {
  68                 assert ( iobuf->head <= iobuf->data );
  69                 assert ( iobuf->data <= iobuf->tail );
  70                 assert ( iobuf->tail <= iobuf->end );
  71                 free_dma ( iobuf->head,
  72                            ( iobuf->end - iobuf->head ) + sizeof ( *iobuf ) );
  73         }
  74 }