63 lines
2.2 KiB
C
63 lines
2.2 KiB
C
#include "../include/dma.h"
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#include "../include/io.h"
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unsigned char MaskReg[8] = {0x0A, 0x0A, 0x0A, 0x0A, 0xD4, 0xD4, 0xD4, 0xD4};
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unsigned char ModeReg[8] = {0x0B, 0x0B, 0x0B, 0x0B, 0xD6, 0xD6, 0xD6, 0xD6};
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unsigned char ClearReg[8] = {0x0C, 0x0C, 0x0C, 0x0C, 0xD8, 0xD8, 0xD8, 0xD8};
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unsigned char PagePort[8] = {0x87, 0x83, 0x81, 0x82, 0x8F, 0x8B, 0x89, 0x8A};
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unsigned char AddrPort[8] = {0x00, 0x02, 0x04, 0x06, 0xC0, 0xC4, 0xC8, 0xCC};
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unsigned char CountPort[8] = {0x01, 0x03, 0x05, 0x07, 0xC2, 0xC6, 0xCA, 0xCE};
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void dma_xfer(unsigned char channel, unsigned long address, unsigned int length,
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unsigned char read) {
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unsigned char page = 0, mode = 0;
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unsigned int offset = 0;
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if (read)
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mode = 0x48 + channel;
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else
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mode = 0x44 + channel;
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page = address >> 16;
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offset = address & 0xFFFF;
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length--;
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_dma_xfer(channel, page, offset, length, mode);
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}
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void _dma_xfer(unsigned char DMA_channel, unsigned char page,
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unsigned int offset, unsigned int length, unsigned char mode) {
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/* 我们不想别的事情来打扰 */
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asm("cli");
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/* 设置DMA通道，以便我们可以正确传输数据，这很简单，只要我们用I/O操作告诉DMA控制器就行了
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*/
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/* 我们将使用这个通道（DMA_channel）*/
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io_out8(MaskReg[DMA_channel], 0x04 | DMA_channel);
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/* 我们先得解除DMA对这个通道的屏蔽，不然用不了 */
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io_out8(ClearReg[DMA_channel], 0x00);
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/* 向DMA发送指定的模式 */
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io_out8(ModeReg[DMA_channel], mode);
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/* 发送偏移量地址，先发送高八位，再发送低八位（因为一次性最多只能发送一个byte）
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*/
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io_out8(AddrPort[DMA_channel], LOW_BYTE(offset));
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io_out8(AddrPort[DMA_channel], HI_BYTE(offset));
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/* 发送数据所在的物理页 */
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io_out8(PagePort[DMA_channel], page);
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/* 发送数据的长度 跟之前一样，先发送低八位，再发送高八位*/
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io_out8(CountPort[DMA_channel], LOW_BYTE(length));
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io_out8(CountPort[DMA_channel], HI_BYTE(length));
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/* 现在我们该做的东西已经全部做完了，所以启用DMA_channel */
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io_out8(MaskReg[DMA_channel], DMA_channel);
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/* 重新让CPU能够接收到中断 */
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asm("sti");
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}
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