dma.bas

static shared As UByte dmaregs(0 To 15)
static shared As Integer dmaon(0 To 3)
static shared As UByte dma16regs(0 To 15)
static shared As Integer dma16on(0 To 3)
static shared As UByte dmapages(0 To 15)


'Sub dma_init() 
        'io_sethandler(&h0000, &h0010, dma_read,      NULL, NULL, dma_write,      NULL, NULL) 
        'io_sethandler(&h0080, &h0008, dma_page_read, NULL, NULL, dma_page_write, NULL, NULL) 
'End Sub

'Sub dma16_init() 
        'io_sethandler(&h00C0, &h0020, dma16_read,    NULL, NULL, dma16_write,    NULL, NULL) 
        'io_sethandler(&h0088, &h0008, dma_page_read, NULL, NULL, dma_page_write, NULL, NULL) 
'End Sub


Sub dma_reset() 
        Dim As Integer c =Any
        dma.wp=0 
        for  c=0 To 15
        	dmaregs(c)=0
        Next
        for  c=0 To 3
                dma.mode(c)=0 
                dma.ac(c)=0 
                dma.cc(c)=0 
                dma.ab(c)=0 
                dma.cb(c)=0 
        Next
        dma.m=0 
        dma16.wp=0 
        for  c=0 To 15 
        	dma16regs(c)=0
        Next
        for  c=0 To 3
                dma16.mode(c)=0 
                dma16.ac(c)=0 
                dma16.cc(c)=0 
                dma16.ab(c)=0 
                dma16.cb(c)=0 
        Next
        dma16.m=0 
End Sub

Function dma_read(byval addr As Ushort ) As UByte 
        Dim As UByte  temp =Any
        Select Case As Const  (addr And &hF)
        	case 0, 2, 4, 6  /'Address registers'/
                dma.wp = dma.wp Xor 1 
                if dma.wp Then Return dma.ac((addr Shr 1) And 3) And &hFF 
                Return dma.ac((addr Shr 1) And 3) Shr 8 

        	Case 1, 3, 5, 7  /'Count registers'/
                dma.wp = dma.wp Xor 1 
                if dma.wp Then Return dma.cc((addr Shr 1) And 3) And &hFF 
                Return dma.cc((addr Shr 1) And 3) Shr 8

        	Case 8  /'Status register'/
                temp=dma.stat 
                dma.stat=0 
                return temp Or 1 
                
        	Case &hD 
                return 0 
                
        End Select
        return dmaregs(addr And &hF) 
End Function

Sub dma_write(byval addr As Ushort, ByVal valor As UByte ) 
        dmaregs(addr And &hF)=valor 
        Select Case As Const  (addr And &hF)
        	case 0, 2, 4, 6  /'Address registers'/
                dma.wp = dma.wp Xor 1 
                if dma.wp Then 
                     dma.ab((addr Shr 1) And 3)=(dma.ab((addr Shr 1) And 3) And &hFF00) Or  valor 
                else
                     dma.ab((addr Shr 1) And 3)=(dma.ab((addr Shr 1) And 3) And &hFF  ) Or (valor Shl 8)
                EndIf
                dma.ac((addr Shr 1) And 3)=dma.ab((addr Shr 1) And 3) 
                dmaon ((addr Shr 1) And 3)=1 
                return 
        	case 1, 3, 5, 7  /'Count registers'/
                dma.wp = dma.wp Xor 1 
                if dma.wp Then 
                     dma.cb((addr Shr 1) And 3)=(dma.cb((addr Shr 1) And 3) And &hFF00) Or  valor 
                else
                     dma.cb((addr Shr 1) And 3)=(dma.cb((addr Shr 1) And 3) And &hFF  ) Or (valor Shl 8)
                EndIf
                dma.cc((addr Shr 1) And 3)=dma.cb((addr Shr 1) And 3) 
                dmaon ((addr Shr 1) And 3)=1 
                return 
        	case 8  /'Control register'/
                dma.command0 = valor 
                return 
        	case &hA  /'Mask'/
                if (valor And 4) Then 
                     dma.m = dma.m Or     (1 Shl (valor And 3)) 
                else
                     dma.m = dma.m And inv(1 Shl (valor And 3))
                EndIf
                return 
        	case &hB  /'Mode'/
                dma.mode(valor And 3)=valor 
                return 
        	case &hC  /'Clear FF'/
                dma.wp=0 
                return 
        	case &hD  /'Master clear'/
                dma.wp=0 
                dma.m=&hF 
                return 
        	case &hF  /'Mask write'/
                dma.m=valor And &hF 
                return 
        End Select
end Sub

Function dma16_read(ByVal addr As UShort ) As UByte 
        Dim As UByte  temp =Any
        addr = addr Shr 1 
        Select Case As Const  (addr And &hF)
        	Case 0 
                if ((dma16.mode(0) Shr 2) And 3)=2 Then 
                        dma16.ac(0)+=1 
                        dma16.cc(0)-=1 
                        if dma16.cc(0)<0 Then 
                                dma16.ac(0)=dma16.ab(0) 
                                dma16.cc(0)=dma16.cb(0) 
                        EndIf
                EndIf
                '''''''''Address registers AC'''''''''''
                ' esto es como "CASE 2,4,6" pero al no llegar, lo pongo aqui
                dma16.wp = dma16.wp Xor 1 
                if dma16.wp Then Return dma16.ac((addr Shr 1) And 3) And &hFF 
                Return dma16.ac((addr Shr 1) And 3) Shr 8 
                '''''''''''''''''''''''''''''''''''''''
                
        	Case 2, 4, 6  /'Address registers AC'/
                dma16.wp = dma16.wp Xor 1 
                if dma16.wp Then Return dma16.ac((addr Shr 1) And 3) And &hFF 
                Return dma16.ac((addr Shr 1) And 3) Shr 8 
                
        	Case 1, 3, 5, 7  /'Count registers CC'/
                dma16.wp = dma16.wp Xor 1 
                if dma16.wp Then Return dma16.cc((addr Shr 1) And 3) And &hFF 
                Return dma16.cc((addr Shr 1) And 3) Shr 8
                
        	Case 8  /'Status register'/
                temp=dma16.stat 
                dma16.stat=0 
                return temp Or 1 
                
        End Select

       return dma16regs(addr And &hF) 
End Function

Sub dma16_write(ByVal addr As UShort , ByVal valor As UByte ) 
        addr = addr Shr 1 
        dma16regs(addr And &hF)=valor 
        Select Case As Const  (addr And &hF)
        	Case 0, 2, 4, 6  /'Address registers'/
                dma16.wp = dma16.wp Xor 1 
                if dma16.wp Then 
                    dma16.ab((addr Shr 1) And 3)=(dma16.ab((addr Shr 1) And 3) And &hFF00) Or  valor 
                else
                    dma16.ab((addr Shr 1) And 3)=(dma16.ab((addr Shr 1) And 3) And &hFF  ) Or (valor Shl 8)
                EndIf
                dma16.ac((addr Shr 1) And 3)=dma16.ab((addr Shr 1) And 3) 
                dma16on ((addr Shr 1) And 3)=1 
                return 
        	Case 1, 3, 5, 7  /'Count registers'/
                dma16.wp = dma16.wp Xor 1 
                if dma16.wp Then 
                    dma16.cb((addr Shr 1) And 3)=(dma16.cb((addr Shr 1) And 3) And &hFF00) Or  valor 
                else
                    dma16.cb((addr Shr 1) And 3)=(dma16.cb((addr Shr 1) And 3) And &hFF  ) Or (valor Shl 8)
                EndIf
                dma16.cc((addr Shr 1) And 3)=dma16.cb((addr Shr 1) And 3) 
                dma16on ((addr Shr 1) And 3)=1 
                return 
        	Case 8  /'Control register'/
                return 
        	Case &hA  /'Mask'/
                if valor And 4 Then 
                    dma16.m = dma16.m   Or   (1 Shl (valor And 3)) 
                else
                    dma16.m = dma16.m And inv(1 Shl (valor And 3))
                EndIf
                return 
        	Case &hB  /'Mode'/
                dma16.mode(valor And 3)=valor 
                return 
        	Case &hC  /'Clear FF'/
                dma16.wp=0 
                return 
        	Case &hD  /'Master clear'/
                dma16.wp=0 
                dma16.m=&hF 
                return 
        	Case &hF  /'Mask write'/
                dma16.m=valor And &hF 
                return 
        End Select
End Sub

Sub dma_page_write(byval addr As Ushort, valor As UByte ) 
        dmapages(addr And &hF)=valor 
        Select Case As Const  (addr And &hF)
        	Case 1 
                dma.page(2)=valor 'IIf(AT,valor,valor And &hF )

        	Case 2 
                dma.page(3)=valor 'IIf(AT,valor,valor And &hF )

        	Case 3 
                dma.page(1)=valor 'IIf(AT,valor,valor And &hF )

        	Case &hB 
                dma16.page(1)=valor 

        End Select
End Sub

Function dma_page_read(byval addr As UShort ) As UByte 
        return dmapages(addr And &hF) 
End Function

' NOTA IMPORTANTE: las rutinas que hay aqui en medio, las he puesto abajo del todo agrupadas
' por que son SOLO para el FDC.BAS, y espero NO usarlo al acabar, y borrarlos

Function readdma1() As UByte 
        Dim As UByte temp=Any

        temp=ram[(dma.ac(1)+(dma.page(1) Shl 16)) And rammask] 
        if dmaon(1)=0 Then 
           Return temp 
        EndIf
        dma.ac(1)+=1 
        dma.cc(1)-=1 
        if (dma.cc(1)<=-1)  And  ((dma.mode(1) And &h10)<>0) Then 
            dma.cc(1)=dma.cb(1) 
            dma.ac(1)=dma.ab(1) 
        ElseIf dma.cc(1)<=-1 Then
				dmaon(1)=0
        EndIf
        return temp 
End Function

Function readdma5() As UShort 
        Dim As UShort temp=Any
        
        temp=ram[((dma16.ac(1) Shl 1)+((dma16.page(1) And inv(1)) Shl 16)  ) And rammask] _ 
         Or (ram[((dma16.ac(1) Shl 1)+((dma16.page(1) And inv(1)) Shl 16)+1) And rammask] Shl 8) 
         
        if dma16on(1)=0 Then 
                return temp 
        EndIf
        dma16.ac(1)+=1 
        dma16.cc(1)-=1 
        if (dma16.cc(1)<=-1)  And  ((dma16.mode(1) And &h10)<>0) Then 
            dma16.cc(1)=dma16.cb(1) 
            dma16.ac(1)=dma16.ab(1) 
        ElseIf dma16.cc(1)<=-1 Then
				dma16on(1)=0
        EndIf
        return temp 
End Function

Sub writedma1(temp As UByte ) 
        if dmaon(1)=0 Then return 
        ram[(dma.ac(1)+(dma.page(1) Shl 16)) And rammask]=temp 
        dma.ac(1)+=1 
        dma.cc(1)-=1 
        if (dma.cc(1)=0)  And  ((dma.mode(1) And &h10)<>0) Then 
            dma.cc(1)=dma.cb(1)+1 
            dma.ac(1)=dma.ab(1) 
        ElseIf dma.cc(1)<=-1 Then
				dmaon(1)=0
        EndIf
End Sub

Sub writedma5(temp As UShort ) 
        if dma16on(1)=0 Then return 
        ram[((dma16.ac(1) Shl 1)+((dma16.page(1) And inv(1)) Shl 16)  ) And rammask]=temp 
        ram[((dma16.ac(1) Shl 1)+((dma16.page(1) And inv(1)) Shl 16)+1) And rammask]=temp Shr 8
        dma16.ac(1)+=1 
        dma16.cc(1)-=1 
        if (dma16.cc(1)<=-1) And ((dma16.mode(1) And &h10)<>0) Then 
            dma16.cc(1)=dma16.cb(1) 
            dma16.ac(1)=dma16.ab(1) 
        ElseIf dma16.cc(1)<=-1 Then
				dma16on(1)=0
        EndIf
End Sub

Function readdma3() As Integer 
        Dim As ubyte temp =any
        temp=ram[((dma.page(3) Shl 16)+dma.ac(3)) And rammask]
        if (dma.m And 8) Then Return -1 
        if (dma.m And 8)=0 Then 
                dma.ac(3)+=1 
                dma.cc(3)-=1 
                if dma.cc(3)=-1 Then 
                    dma.m = dma.m Or 8 
                    dma.stat = dma.stat Or 8 
                EndIf
        EndIf
        return temp 
End Function

'refresread en X86.bas
Declare Sub refreshread()
Sub readdma0() 
        'if (AT) Then 
        	 ppi.pb = ppi.pb Xor &h10   ' siempre es AT      
        'EndIf
        if dma.command0 And 4 Then return 
        'refreshread() ' lo anulo, por que sin el parece funcionar bien
        if dma.m And 1 Then return 
        
       dma.ac(0)+=2 
       dma.cc(0)-=1 
       if dma.cc(0)=-1 Then 
           dma.stat = dma.stat Or 1 
           dma.ac(0)= dma.ab(0) 
           dma.cc(0)= dma.cb(0) 
       EndIf
End Sub























' al parecer, esta rutina es SOLO para el modulo FDC!!!!
Function _dma_read(addr As ULong ) As UByte 
        Select Case  (addr And &hFFFF8000)
        	Case &hA0000, &hA8000 
                Return vram[addr-&hA0000]
                'Return leeram1(addr) 'video_read_a000(addr) 
        	Case &hB0000 
                Return vram[addr-&hB0000]
                'Return leeram1(addr) 'video_read_b000(addr) 
        	Case &hB8000 
                Return vram[addr-&hB8000]
                'Return leeram1(addr) 'video_read_b800(addr) 
        End Select
        If (isram(addr Shr 16)) Then return ram[addr] 
        return &hff 
End Function

' al parecer, esta rutina es SOLO para el modulo FDC!!!!
Sub _dma_write(addr As ULong , valor As UByte ) 
        Select Case  (addr And &hFFFF8000)
        	Case &hA0000, &hA8000 
                vram[addr-&hA0000]=valor
                'grabaram1(addr,valor)' video_write_a000(addr,valor) 
                return 
        	Case &hB0000 
                vram[addr-&hB0000]=valor
                'grabaram1(addr,valor)' video_write_b000(addr,valor) 
                return 
        	Case &hB8000 
                vram[addr-&hB8000]=valor'
                'grabaram1(addr,valor)' video_write_b800(addr,valor) 
                return 
        	Case &hC0000, &hC8000, &hD0000, &hD8000 
        			 Return
        	Case &hE0000, &hE8000, &hF0000, &hF8000 
                return 
       End Select
       if (isram(addr Shr 16)) Then ram[addr]=valor 
End Sub