Initial commit
This commit is contained in:
Gwen Gourevich
378
LIB386/LIB_SAMP/DMA_CODE.ASM
Normal file
378
LIB386/LIB_SAMP/DMA_CODE.ASM
Normal file
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.DATA
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Status EQU 08h ;DMAC status port (read) \ same port
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Command EQU 08h ;DMAC command port (write) / (read/write)
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Request EQU 09h ;DMAC channel request (write-only)
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DMA_Mask EQU 0Ah ;DMAC DMA_Mask (write-only)
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Mode EQU 0Bh ;DMAC mode (write)
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byte_ptr EQU 0Ch ;byte pointer flip-flop
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addr EQU 000h ; per-channel base address
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count EQU 001h ; per-channel byte count
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read_cmd EQU 058h ; autoinitialising read
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write_cmd EQU 054h ; auto write
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set_cmd EQU 000h ; DMA_Mask set (enable dma)
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reset_cmd EQU 004h ; DMA_Mask reset (disable)
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page_table DW 00087h ; channel 0
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DW 00083h ; channel 1
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DW 00081h ; channel 2
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DW 00082h ; channel 3
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DW 0FFFFh ; ch 4 (not used)
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DW 0008Bh ; ch 5
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DW 00089h ; ch 6
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DW 0008Ah ; ch 7
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dmac2 DB 0 ; Flag set to non-zero when using the 2nd DMA controller
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.CODE
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MACRO adjust reg ; Adjust register port for 2nd DMA cont
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local no_adjust
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cmp byte ptr[dmac2], 0
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jz no_adjust
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shl reg, 1
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add reg, 0C0h
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no_adjust:
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ENDM adjust
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;+---------------------------------------------------------------------------+
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;| int dma_setup(int Channel, char far *Buffer, unsigned Length) |
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;| ------------------------------------------------------------------------- |
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;| Channel = 0-7 |
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;| Buffer = Address of data to transfer |
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;| Length = Length of data to transfer |
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;| ------------------------------------------------------------------------- |
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;| Returns: 0 if no errors (dma_errno == 0) |
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;| -1 if errors occurred (dma_errno set to indicate error.) |
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;+---------------------------------------------------------------------------+
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dma_setup PROC USES EBX,\
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Channel:DWORD, Buffer:DWORD, Len:DWORD
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;Convert 20-bit physical address of buffer into page:offset
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mov edi, Buffer
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mov ecx, edi
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shr ecx, 8
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; ch:di == The physical buffer base.
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; Adjust channel number
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mov byte ptr[dmac2], 0
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mov bx, Channel
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cmp bx, 4
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jb OkChannel
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and bx, 3
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mov byte ptr[dmac2], 1
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OkChannel:
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; BX contains the adjusted channel number
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mov si, read_cmd
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add si, bx
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mov cl, set_cmd ;allow dma requests
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add cl, bl
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;si contains READ/WRITE command for DMA controller
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;cl contains confirmation command for DMA controller
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shl bx, 1
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;bx == Port # Channel*2
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;-------------------------------------------------------------------------
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; Calculations have been done ahead of time to minimize time with
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; interrupts disabled.
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;
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; edi (ch:di) == physical base address (must be on word boundary for 16 bits)
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;
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; cl == Confirmation command (Unmasks the channel)
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;
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; bx == I/O port Channel*2 (This is where the address is written)
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;
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; si == Mode command for DMA
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;-------------------------------------------------------------------------
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; Now we shift the address and word count right one bit if in 16 bit mode.
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cmp [dmac2], 0
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jz AddrOk
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shr ch, 1
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rcr di, 1
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shl ch, 1
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shr [Len], 1 ;Odd byte lengths are rounded down
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AddrOk:
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;The "byte pointer" is also known as the LSB/MSB flip flop.
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;By writing any value to it, the DMA controller registers are prepared
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;to accept the address and length values LSB first.
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mov dx, byte_pt ;Reset byte pointer Flip/flop
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adjust dx
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out dx, al
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mov dx, bx ;dx=DMAC Base Address port
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adjust dx
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mov ax, di ;ax=LSW of 20-bit address
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out dx, al ;Store LSB
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mov al, ah
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out dx, al ;Store MSB
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;Write length to port (Channel * 2 + 1)
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inc dx ;dx=DMAC Count port
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mov eax, Len
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out dx, al ;Write LSB of Length
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mov al, ah
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out dx, al ;Write MSB
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;Write page to port page_table[channel]
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mov ebx, Channel
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shl bx, 1
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mov dx, word ptr[OFFSET page_table + bx]
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mov al, ch ;al=Page number
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out dx, al ;Store the page
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;Write Readcmd for channel to Mode port
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mov dx, Mode ;dx=DMAC mode register
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adjust dx
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mov ax, si ;Load pre-calculated mode
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out dx, al ;Write it to the DSP
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mov dx, DMA_Mask ;dx=DMAX DMA_Mask register
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adjust dx
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mov al, cl ;al=pre-calulated DMA_Mask value
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out dx, al ;Write DMA_Mask (allow dma on this channel)
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ret
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dma_setup ENDP
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;+---------------------------------------------------------------------------+
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;| int prevent_dma(int Channel) |
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;| ------------------------------------------------------------------------- |
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;| Channel = 0-7 |
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;| Prevents DMA requests from Channel by masking bit in DMA_C. |
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;| ------------------------------------------------------------------------- |
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;+---------------------------------------------------------------------------+
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prevent_dma PROC ,\
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Channel:DWORD
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; Check channel number range
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mov dx, DMA_Mask
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mov eax, Channel
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cmp al, 4
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jb OkChannel
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and al, 3
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shl dx, 1
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add dx, 0C0h
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OkChannel:
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add al, reset_cmd ; Add disable DMA requests
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out dx, al
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ret
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prevent_dma ENDP
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;+---------------------------------------------------------------------------+
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;| int allow_dma(int Channel) |
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;| ------------------------------------------------------------------------- |
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;| Channel = 0-7 |
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;| Unmasks DMA on the specified channel. |
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;| ------------------------------------------------------------------------- |
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;+---------------------------------------------------------------------------+
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allow_dma PROC ,\
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Channel:DWORD
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; Check channel number range
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mov dx, DMA_Mask
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mov eax, Channel
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cmp al, 4
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jb OkChannel
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and al, 3
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shl dx, 1
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add dx, 0C0h
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OkChannel:
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add al, set_cmd ; Add enable DMA requests
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out dx, al
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ret
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allow_dma ENDP
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;+---------------------------------------------------------------------------+
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;| int dma_count(Channel) |
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;| ------------------------------------------------------------------------- |
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;| Channel = 0-7 |
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;| ------------------------------------------------------------------------- |
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;| Returns: -1 if DMA transaction completed |
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;| else returns the number of bytes/words left to transfer |
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;+---------------------------------------------------------------------------+
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PROC dma_count ,\
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Channel:DWORD
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mov eax, Channel
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mov dx, ax
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and dx, 3
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shl dx, 1
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add dx, count
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cmp al, 4
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jb OkChannel
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shl dx, 1
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add dx, 0C0h
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OkChannel:
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xor eax, eax
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cli
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in al, dx
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mov ah, al
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in al, dx
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sti
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xchg al, ah
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ret
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dma_count ENDP
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;+---------------------------------------------------------------------------+
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;| unsigned dma_addr(Channel) |
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;| ------------------------------------------------------------------------- |
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;| Channel = 0-7 |
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;| ------------------------------------------------------------------------- |
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;| Returns: Current address word of that channel |
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;| Value must be multiplied by 2 for a 16-bit channel. |
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;| It is best to start at offset 0, ie on a 64K boundary |
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;+---------------------------------------------------------------------------+
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dma_addr PROC ,\
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Channel:DWORD
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mov eax, Channel
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mov dx, ax
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and dx, 3
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shl dx, 1
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cmp al, 4
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jb OkChannel
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shl dx, 1
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add dx, 0C0h
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OkChannel:
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xor eax, eax
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cli
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in al, dx
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mov ah, al
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in al, dx
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sti
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xchg al, ah
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ret
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dma_addr ENDP
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VOID *DMABuffer, *DMAAllocBuffer;
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BYTE LockedDMARegion;
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#define MAX_DMABUFFERATTEMPTS 10;
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;+---------------------------------------------------------------------------+
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;| BYTE *AlignOn4KBoundry( BYTE *Buf ) |
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;| ------------------------------------------------------------------------- |
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;| Align Buf to the nearest 4K page |
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;+---------------------------------------------------------------------------+
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#define AlignOn4KBoundry(Buf) ((Buf + 0x00000FFF) & 0xFFFFF000)
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;+---------------------------------------------------------------------------+
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;| BYTE *AllocateDMABuffer( WORD BufferSize ) |
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;| ------------------------------------------------------------------------- |
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;| BufferSize = 0-64K |
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;| ------------------------------------------------------------------------- |
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;| Returns: Buffer if successful |
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;| NULL if error |
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;+---------------------------------------------------------------------------+
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BYTE *AllocateDMABuffer( WORD BufferSize )
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{
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VOID *Tried[ MAX_DMABUFFERATTEMPTS ] ;
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VOID *Buf, *DMAAddr ;
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int Tries, Error ;
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for (Tries = 0; Tries < MAX_DMABUFFERATTEMPTS; Tries++)
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Tried[ Tries ] = NULL ;
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Tries = 0;
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LockedDMARegion = FALSE;
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do
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{
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// printf( "DMA buffer allocation attempt: %d\n", Tries + 1 ) ;
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if ((DMAAllocBuffer = (VOID *)DosMalloc( BufferSize + 0xFFF)) != NULL)
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{
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DMABuffer = AlignOn4KBoundry(DMAAllocBuffer);
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if ( ((LONG)DMABuffer & 0xF0000) !=
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(((LONG)DMABuffer + BufferSize) & 0xF0000) )
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{
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Tried[ Tries ] = DMAAllocBuffer ;
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DMAAllocBuffer = NULL ;
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DMABuffer = NULL ;
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}
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}
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Tries++ ;
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DMAAllocBuf = Buf;
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DMABuffer = DMAAddr ;
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}
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while ((DMAAllocBuf == NULL) && (Tries < MAX_DMABUFFERATTEMPTS)) ;
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for (wTries = 0; wTries < MAX_DMABUFFERATTEMPTS; wTries++)
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{
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if (alpTried[ wTries ])
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free( alpTried[ wTries ] ) ;
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else
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break ;
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}
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return( DMABuffer ) ;
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;+---------------------------------------------------------------------------+
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;| VOID FreeDMABuffer( VOID ) |
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;| ------------------------------------------------------------------------- |
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;| Free the DMA buffer |
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;+---------------------------------------------------------------------------+
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VOID FreeDMABuffer( VOID )
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{
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if (LockedDMARegion)
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UnlockDMARegion( &gDDS, 0 ) ;
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if (DMAAllocBuf)
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{
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free( glpDMAAllocBuf ) ;
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DMAAllocBuf = NULL ;
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}
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}
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