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 <errno.h>
  21 #include <gpxe/malloc.h>
  22 #include <gpxe/iobuf.h>
  23
  24 /** @file
  25  *
  26  * I/O buffers
  27  *
  28  */
  29
  30 /**
  31  * Allocate I/O buffer
  32  *
  33  * @v len       Required length of buffer
  34  * @ret iobuf   I/O buffer, or NULL if none available
  35  *
  36  * The I/O buffer will be physically aligned to a multiple of
  37  * @c IOBUF_SIZE.
  38  */
  39 struct io_buffer * alloc_iob ( size_t len ) {
  40         struct io_buffer *iobuf = NULL;
  41         void *data;
  42
  43         /* Pad to minimum length */
  44         if ( len < IOB_ZLEN )
  45                 len = IOB_ZLEN;
  46
  47         /* Align buffer length */
  48         len = ( len + __alignof__( *iobuf ) - 1 ) &
  49                 ~( __alignof__( *iobuf ) - 1 );
  50
  51         /* Allocate memory for buffer plus descriptor */
  52         data = malloc_dma ( len + sizeof ( *iobuf ), IOB_ALIGN );
  53         if ( ! data )
  54                 return NULL;
  55
  56         iobuf = ( struct io_buffer * ) ( data + len );
  57         iobuf->head = iobuf->data = iobuf->tail = data;
  58         iobuf->end = iobuf;
  59         return iobuf;
  60 }
  61
  62 /**
  63  * Free I/O buffer
  64  *
  65  * @v iobuf     I/O buffer
  66  */
  67 void free_iob ( struct io_buffer *iobuf ) {
  68         if ( iobuf ) {
  69                 assert ( iobuf->head <= iobuf->data );
  70                 assert ( iobuf->data <= iobuf->tail );
  71                 assert ( iobuf->tail <= iobuf->end );
  72                 free_dma ( iobuf->head,
  73                            ( iobuf->end - iobuf->head ) + sizeof ( *iobuf ) );
  74         }
  75 }
  76
  77 /**
  78  * Ensure I/O buffer has sufficient headroom
  79  *
  80  * @v iobuf     I/O buffer
  81  * @v len       Required headroom
  82  *
  83  * This function currently only checks for the required headroom; it
  84  * does not reallocate the I/O buffer if required.  If we ever have a
  85  * code path that requires this functionality, it's a fairly trivial
  86  * change to make.
  87  */
  88 int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len ) {
  89
  90         if ( iob_headroom ( iobuf ) >= len )
  91                 return 0;
  92         return -ENOBUFS;
  93 }
  94