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 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <stdint.h>
  22 #include <errno.h>
  23 #include <gpxe/malloc.h>
  24 #include <gpxe/iobuf.h>
  25
  26 /** @file
  27  *
  28  * I/O buffers
  29  *
  30  */
  31
  32 /**
  33  * Allocate I/O buffer
  34  *
  35  * @v len       Required length of buffer
  36  * @ret iobuf   I/O buffer, or NULL if none available
  37  *
  38  * The I/O buffer will be physically aligned to a multiple of
  39  * @c IOBUF_SIZE.
  40  */
  41 struct io_buffer * alloc_iob ( size_t len ) {
  42         struct io_buffer *iobuf = NULL;
  43         void *data;
  44
  45         /* Pad to minimum length */
  46         if ( len < IOB_ZLEN )
  47                 len = IOB_ZLEN;
  48
  49         /* Align buffer length */
  50         len = ( len + __alignof__( *iobuf ) - 1 ) &
  51                 ~( __alignof__( *iobuf ) - 1 );
  52
  53         /* Allocate memory for buffer plus descriptor */
  54         data = malloc_dma ( len + sizeof ( *iobuf ), IOB_ALIGN );
  55         if ( ! data )
  56                 return NULL;
  57
  58         iobuf = ( struct io_buffer * ) ( data + len );
  59         iobuf->head = iobuf->data = iobuf->tail = data;
  60         iobuf->end = iobuf;
  61         return iobuf;
  62 }
  63
  64 /**
  65  * Free I/O buffer
  66  *
  67  * @v iobuf     I/O buffer
  68  */
  69 void free_iob ( struct io_buffer *iobuf ) {
  70         if ( iobuf ) {
  71                 assert ( iobuf->head <= iobuf->data );
  72                 assert ( iobuf->data <= iobuf->tail );
  73                 assert ( iobuf->tail <= iobuf->end );
  74                 free_dma ( iobuf->head,
  75                            ( iobuf->end - iobuf->head ) + sizeof ( *iobuf ) );
  76         }
  77 }
  78
  79 /**
  80  * Ensure I/O buffer has sufficient headroom
  81  *
  82  * @v iobuf     I/O buffer
  83  * @v len       Required headroom
  84  *
  85  * This function currently only checks for the required headroom; it
  86  * does not reallocate the I/O buffer if required.  If we ever have a
  87  * code path that requires this functionality, it's a fairly trivial
  88  * change to make.
  89  */
  90 int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len ) {
  91
  92         if ( iob_headroom ( iobuf ) >= len )
  93                 return 0;
  94         return -ENOBUFS;
  95 }
  96