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Annotation of kernel/machdep/i386/dma_buf.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /*
        !            26:  * Copyright (c) 1992 NeXT Computer, Inc.
        !            27:  *
        !            28:  * dma_buf.c  -- DMA buffer handling.
        !            29:  *
        !            30:  * HISTORY
        !            31:  *
        !            32:  * 26 August 1992 ? at NeXT
        !            33:  *     Created.
        !            34:  */
        !            35: 
        !            36: #import <mach/mach_types.h>
        !            37: 
        !            38: #import <machdep/i386/dma_buf_internal.h>
        !            39: #import <machdep/i386/dma_exported.h>
        !            40: 
        !            41: dma_buf_type_t         dma_buf_sm, dma_buf_lg;
        !            42: 
        !            43: static inline int is_aligned( void *addr, unsigned int alignment )
        !            44: {
        !            45:     return (((unsigned int)addr & (alignment - 1)) == 0);
        !            46: }
        !            47: void
        !            48: dma_buf_initialize(
        !            49:     void
        !            50: )
        !            51: {
        !            52:     int maxbufs = DMA_BUF_LG_LEN / DMA_BUF_SM_LEN + 1;
        !            53:     dma_buf_t buf, bufs[maxbufs];
        !            54:     int nbufs = 0;
        !            55:     
        !            56:     dma_buf_sm.create_fcn = dma_buf_sm_create;
        !            57:     dma_buf_lg.create_fcn = dma_buf_lg_create;
        !            58:     
        !            59:     /*
        !            60:      * Allocate small buffers until the next buffer
        !            61:      * will be on a large-buffer boundary.
        !            62:      * This makes assumptions about the way alloc_cnvmem works -- FIXME!
        !            63:      */
        !            64:     do {
        !            65:        if (dma_buf_alloc(&buf, DMA_BUF_SM_LEN) != TRUE)
        !            66:            break;
        !            67:        bufs[nbufs++] = buf;
        !            68:     } while (maxbufs-- && 
        !            69:            !is_aligned((char *)buf._ptr+DMA_BUF_SM_LEN, DMA_BUF_LG_LEN));
        !            70:     while (nbufs)
        !            71:        dma_buf_free(&bufs[(nbufs--) - 1]);
        !            72:     
        !            73:     /*
        !            74:      * Now create one large buffer.
        !            75:      */
        !            76:     if (dma_buf_alloc(&buf, DMA_BUF_LG_LEN) == TRUE)
        !            77:        dma_buf_free(&buf);
        !            78: }
        !            79: 
        !            80: boolean_t
        !            81: dma_buf_alloc(
        !            82:     dma_buf_t          *buf,
        !            83:     vm_size_t          len
        !            84: )
        !            85: {
        !            86:     dma_buf_region_t   *ptr;
        !            87:     dma_buf_type_t     *buft;
        !            88:     int                        s;
        !            89:     
        !            90:     if (len > DMA_BUF_LG_LEN)
        !            91:        return (FALSE);
        !            92:     else if (len > DMA_BUF_SM_LEN)
        !            93:        buft = &dma_buf_lg;
        !            94:     else
        !            95:        buft = &dma_buf_sm;
        !            96: 
        !            97:     s = spldma();
        !            98: 
        !            99:     if (ptr = buft->free_head) {
        !           100:        buft->free_head = ptr->next;
        !           101:        buft->free_count--;
        !           102:     }
        !           103:     else {
        !           104:        ptr = (*buft->create_fcn)();
        !           105:        if (ptr)
        !           106:            buft->total_count++;
        !           107:     }
        !           108: 
        !           109:     splx(s);
        !           110:     
        !           111:     if (ptr == 0)
        !           112:        return (FALSE);
        !           113: 
        !           114:     buf->_ptr = (void *)ptr;
        !           115:     buf->_type = (void *)buft;
        !           116:     
        !           117:     return (TRUE);
        !           118: }
        !           119: 
        !           120: void
        !           121: dma_buf_free(
        !           122:     dma_buf_t          *buf
        !           123: )
        !           124: {
        !           125:     dma_buf_region_t   *ptr;
        !           126:     dma_buf_type_t     *buft;
        !           127:     int                        s;
        !           128:     
        !           129:     if ((ptr = (dma_buf_region_t *)buf->_ptr) == 0)
        !           130:        return;
        !           131:        
        !           132:     buft = (dma_buf_type_t *)buf->_type;
        !           133: 
        !           134:     s = spldma();
        !           135:     
        !           136:     ptr->next = buft->free_head;
        !           137:     buft->free_head = ptr;
        !           138:     buft->free_count++;        
        !           139:     
        !           140:     splx(s);
        !           141: 
        !           142:     buf->_ptr = 0;
        !           143:     buf->_type = 0;
        !           144: }
        !           145: 
        !           146: static
        !           147: dma_buf_region_t *
        !           148: dma_buf_sm_create(
        !           149:     void
        !           150: )
        !           151: {
        !           152:     caddr_t buf = (caddr_t)alloc_cnvmem(DMA_BUF_SM_LEN, DMA_BUF_SM_LEN);
        !           153:     if (buf)
        !           154:        bzero(buf,DMA_BUF_SM_LEN);
        !           155:     return ((dma_buf_region_t *)buf );
        !           156: }
        !           157: 
        !           158: /*
        !           159:  * Eventually, this should allocate small buffers until we get
        !           160:  * to a large buffer alignment boundary.
        !           161:  */
        !           162:  
        !           163: static
        !           164: dma_buf_region_t *
        !           165: dma_buf_lg_create(
        !           166:     void
        !           167: )
        !           168: {
        !           169:     caddr_t buf = (caddr_t)alloc_cnvmem(DMA_BUF_LG_LEN, DMA_BUF_LG_LEN);
        !           170:     if (buf)
        !           171:        bzero(buf,DMA_BUF_LG_LEN);
        !           172:     return ((dma_buf_region_t *)buf );
        !           173: }

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