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#define DMASTATUSREG 0x8
#define DMA8SINGLEMASKREG 0xa
#define DMA16SINGLEMASKREG 0xd4
#define DMA8MASTERMASKREG 0xf
#define DMA16MASTERMASKREG 0xde
#define DMA8CLEARFLIPFLOP 0xc
#define DMA16CLEARFLIPFLOP 0xd8
#define DMA8BASE 0x0
#define DMA16BASE 0xc0
ULONG page[8] = { 0x87, 0x83, 0x81, 0x82, 0x8f, 0x8b, 0x89, 0x8a };
VOID __inline UnmaskDmaChannel(ULONG channel){
ASSERT ( channel<8 && channel!=4 );
if (channel<4) {
__asm {
mov eax,channel out DMA8SINGLEMASKREG,al
}
}else if (channel<8) {
__asm {
mov eax,channel sub eax,4 out DMA16SINGLEMASKREG,al
}
}
}
VOID __inline MaskDmaChannel(ULONG channel){
ASSERT ( channel<8 && channel!=4 );
if (channel<4) {
__asm {
mov eax,channel or eax,0x4 out DMA8SINGLEMASKREG,al
}
}else if (channel<8) {
__asm {
mov eax,channel out DMA16SINGLEMASKREG,al
}
}
}
// This reads the DMA controller mask register.
ULONG __inline ReadDMAMask(VOID){
__asm { xor eax,eax in al,DMA8MASTERMASKREG ror eax,4 in al,DMA16MASTERMASKREG and al,0xf rol eax,4 }
}
VOID __inline ReadDmaPosition(ULONG channel, PULONG pCurrentDmaPosition){
ASSERT ( channel<8 && channel!=4 );
if (channel<4) {
__asm { // First clear the flip flop.
xor eax,eax out DMA8CLEARFLIPFLOP, al
// Read low byte and save it away.
mov edx, channel shl edx, 1 in al, dx ror eax,8
// Read high byte and save it away.
in al, dx ror eax,8
// Read page byte.
shl edx, 1 add edx, offset page mov edx, dword ptr[edx] in al, dx ror eax,8
// Read hi-page byte. Ignore if 0xff.
add edx,0x400 in al, dx sub al, 0xff jz done8 add al, 0xffdone8: ror eax,8
mov edx, pCurrentDmaPosition mov dword ptr [edx], eax
}
}
else if (channel<8) {
__asm { // First clear the flip flop.
xor eax,eax out DMA16CLEARFLIPFLOP, al
// Read low byte and save it away.
mov edx, channel sub edx, 4 shl edx, 2 add edx, DMA16BASE in al, dx ror eax,8
// Read high byte and save it away.
// We left shift bottom 16 bits by 1 and or top bit into page.
in al, dx ror eax,7 mov ah, al
// Read page byte.
mov edx, channel shl edx, 2 add edx, offset page mov edx, dword ptr[edx] in al, dx
// Or in bit 15 of word address and save away page byte.
or al, ah ror eax,8
// Read hi-page byte. Ignore if 0xff.
add edx,0x400 in al, dx sub al, 0xff jz done16 add al, 0xffdone16: ror eax,8
mov edx, pCurrentDmaPosition mov dword ptr [edx], eax
}
}
}
VOID __inline ReadDmaCount(ULONG channel, PULONG pCurrentDmaCount){
ASSERT ( channel<8 && channel!=4 );
if (channel<4) {
__asm { // First clear the flip flop.
xor eax,eax out DMA8CLEARFLIPFLOP, al
// Read low byte and save it away.
mov edx, channel shl edx, 1 inc edx in al, dx ror eax,8
// Read high byte and fixup count.
in al, dx rol eax,8
mov edx, pCurrentDmaCount mov dword ptr [edx], eax
}
}
else if (channel<8) {
__asm { // First clear the flip flop.
xor eax,eax out DMA16CLEARFLIPFLOP, al
// Read low byte and save it away.
mov edx, channel sub edx, 4 shl edx, 2 add edx, 2 add edx, DMA16BASE in al, dx ror eax,8
// Read high byte and fixup count.
in al, dx rol eax,9
mov edx, pCurrentDmaCount mov dword ptr [edx], eax
}
}
}
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