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int.asm
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int.asm
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; -----------------------------------------------------------------
; Implements a jump table to select various interrupt routines.
; Input:
; BP - offset to the function table
; AH - function number
; -----------------------------------------------------------------
INT_Dispatch:
push bx
mov bl, ah
xor bh, bh
shl bx, 1
add bp, bx
pop bx
call [cs:bp]
ret
INT_Unimplemented:
ret
; -----------------------------------------------------------------
; INT 10 - screen functions moved to screen.asm
; -----------------------------------------------------------------
; -----------------------------------------------------------------
; INT 11 - equipment list.
; -----------------------------------------------------------------
INT_11:
INT_Debug 11h
; Detect 8087 processor
call INT_11_CPU
and ax, 0001h
shl ax, 1
; 2 disk drives, MDA card, 64K+ memory, 1 serial port
add ax, 037Dh
iret
; -----------------------------------------------------------------
; Equipment flags.
; -----------------------------------------------------------------
EQUIPMENT_8087 equ 1
EQUIPMENT_V20 equ 2
INT_11_CPU:
push cx
push bx
; Test if 8087 present
fninit
mov cx, 3
INT_11_CPU_8087:
loop INT_11_CPU_8087
mov bx, sp
sub bx, 2
mov [ss:bx], ax
fnstcw [ss:bx]
cmp [ss:bx], word 03FFh
jne INT_11_CPU_No8087
mov cl, EQUIPMENT_8087
INT_11_CPU_No8087:
pop bx
pop cx
ret
db 60h ; PUSHA
stc
jnc INT_11_CPU_NoV20
db 61h ; POPA
or cl, EQUIPMENT_V20
INT_11_CPU_NoV20:
mov al, cl
pop bx
pop cx
ret
; -----------------------------------------------------------------
; INT 12 - memory size.
; -----------------------------------------------------------------
INT_12:
INT_Debug 12h
mov ax, (MemTop-40h)/64
iret
; -----------------------------------------------------------------
; INT 13 - disk functions.
; -----------------------------------------------------------------
INT_13:
INT_Debug 13h
cmp ah, 1Bh
ja INT_13_Ret
push bp
mov bp, INT_13_Functions
call INT_Dispatch
pop bp
retf 2
INT_13_Ret:
iret
INT_13_Functions:
dw INT_13_OK
dw INT_13_01
dw INT_13_02
dw INT_13_03
dw INT_13_OK
dw INT_13_Error
dw INT_13_Error
dw INT_13_Error
dw INT_13_08
dw INT_13_Error
dw INT_13_Error
dw INT_13_Error
dw INT_13_OK
dw INT_13_OK
dw INT_13_Error
dw INT_13_Error
dw INT_13_OK
dw INT_13_Error
dw INT_13_Error
dw INT_13_Error
dw INT_13_Error
dw INT_13_15
dw INT_13_16
dw INT_13_Error
dw INT_13_Error
dw INT_13_Error
dw INT_13_Error
INT_13_HD:
cmp dl, 080h
jne INT_13_HD_1
jmp SD_Handle
INT_13_HD_1:
ret
; -----------------------------------------------------------------
; INT 13 function 00 - reset drive.
; -----------------------------------------------------------------
INT_13_OK:
clc
ret
INT_13_Error:
stc
mov al, 02h
ret
; -----------------------------------------------------------------
; INT 13 function 01 - get status.
; -----------------------------------------------------------------
INT_13_01:
clc
xor al, al
ret
; -----------------------------------------------------------------
; INT 13 function 02 - disk read.
; INT 13 function 03 - disk write.
; -----------------------------------------------------------------
INT_13_02:
test dl, 80h
jnz INT_13_HD
INT_13_02_Floppy:
mov bp, 0
jmp INT_13_Common
INT_13_03:
test dl, 80h
jnz INT_13_HD
mov bp, 1
INT_13_Common:
push es
push cx
push ax
push ax
call INT_13_Logical
pop cx
xor ch, ch
INT_13_02_Loop:
call INT_13_Disk
jc INT_13_02_Error
inc ax
inc ch
cmp ch, cl
jne INT_13_02_Loop
INT_13_02_Break:
mov al, ch
xor ah, ah
INT_13_02_Ret:
pop cx
pop cx
pop es
ret
INT_13_02_Error:
mov al, ch
jmp INT_13_02_Ret
; -----------------------------------------------------------------
; Calculate logical sector number from PC geometry.
; Input:
; CL - physical sector number
; DH - physical head number
; CH - physical track number
; Output:
; AX - logical sector number
; -----------------------------------------------------------------
INT_13_Logical:
push bx
push ds
mov ax, Data_Segment
mov ds, ax
mov al, ch
xor ah, ah
mov bl, 2
mul bl
add al, dh
mov bl, 9
mul bl
mov bl, cl
dec bl
xor bh, bh
add ax, bx
pop ds
pop bx
ret
; -----------------------------------------------------------------
; Read or write PC sector
; Input:
; BP - 0 for disk read, 1 for disk write
; AX - 256-byte sector number
; DL - drive number
; ES:BX - buffer address
; -----------------------------------------------------------------
INT_13_Disk:
push cx
push ax
; Convert 512- to 256-byte sectors
push ds
mov cx, Data_Segment
mov ds, cx
mov cl, 2
xor ch, ch
push dx
mul cx
pop dx
pop ds
; Check if read across 64 kB boundary
push ax
push bx
mov ax, es
shl ax, 1
shl ax, 1
shl ax, 1
shl ax, 1
add ax, bx
test ax, ax
jz INT_13_Disk_Zero
xchg ax, bx
mov ax, 1
mul cl
xchg al, ah
add ax, bx
jc INT_13_Disk_DMA_Error
pop bx
pop ax
; Read physical sectors
INT_13_Disk_Loop:
push ax
call IPC_SectorCalc
call IPC_SectorAccess
cmp ax, 3030h
jz INT_13_Disk_NoError
pop ax
pop ax
pop cx
stc
mov ah, 2
ret
INT_13_Disk_NoError:
; Check if we were reading on the 0000 boundary
; If yes, move the sector 2 bytes below and restore overwritten word
test ch, 01h
jz INT_13_NotZero
push ds
push si
push di
mov di, es
mov ds, di
sub bx, 2
mov si, bx
mov di, bx
push cx
mov cx, 128
lodsw
rep movsw
pop cx
xor ch, ch
stosw
pop di
pop si
pop ds
INT_13_NotZero:
mov ax, es
add ax, 16
mov es, ax
pop ax
inc ax
loop INT_13_Disk_Loop
pop ax
pop cx
clc
ret
; Fake "read across 64 boundary" error
INT_13_Disk_DMA_Error:
pop bx
pop ax
pop ax
pop cx
stc
mov ah, 9
ret
; Read on 0000-aligned address: move the pointer +2 bytes
INT_13_Disk_Zero:
pop bx
; Remember the word that will be overwritten
mov ax, [es:bx+256]
cmp bp, 1
jne INT_13_Disk_NotWrite
; If writing, move the sector 2 bytes up
push ds
push si
push di
mov si, es
mov ds, si
mov si, bx
add si, 254
mov di, bx
add di, 256
std
push cx
mov cx, 128
rep movsw
pop cx
cld
pop di
pop si
pop ds
INT_13_Disk_NotWrite:
mov [es:bx], ax
add bx, 2
pop ax
mov ch, 01h
jmp INT_13_Disk_Loop
; -----------------------------------------------------------------
; INT 13 function 08 - get drive parameters.
; -----------------------------------------------------------------
INT_13_08:
test dl, 80h
jz INT_13_08_Floppy
jmp INT_13_HD
INT_13_08_Floppy:
clc
xor ah, ah
mov bl, 03h
mov cx, 5009h
mov dx, 0102h
mov di, INT_1E
push cs
pop es
ret
; -----------------------------------------------------------------
; INT 13 function 15 - get disk change type.
; -----------------------------------------------------------------
INT_13_15:
test dl, 80h
jz INT_13_15_Floppy
jmp INT_13_HD
INT_13_15_Floppy:
clc
mov ah, 01h
ret
; -----------------------------------------------------------------
; INT 13 function 16 - get disk change flag.
; -----------------------------------------------------------------
INT_13_16:
clc
mov ah, 01h
ret
; -----------------------------------------------------------------
; INT 14 - serial functions.
; -----------------------------------------------------------------
INT_14:
INT_Debug 14h
cmp ah, 03h
ja INT_14_Ret
push bp
mov bp, INT_14_Functions
call INT_Dispatch
pop bp
INT_14_Ret:
iret
INT_14_Functions:
dw INT_14_00
dw INT_14_01
dw INT_14_02
dw INT_14_03
; -----------------------------------------------------------------
; INT 14 function 00 - initialize serial port (unimplemented).
; -----------------------------------------------------------------
INT_14_00:
push ax
call IPC_SerialConvert
call IPC_SerialParams
pop ax
ret
; -----------------------------------------------------------------
; INT 14 function 01 - send character.
; -----------------------------------------------------------------
INT_14_01:
test dx, dx
jnz INT_14_NoPort
call IPC_SerialOut
xor ah, ah
ret
INT_14_NoPort:
ret
; -----------------------------------------------------------------
; INT 14 function 02 - receive character.
; -----------------------------------------------------------------
INT_14_02:
test dx, dx
jnz INT_14_NoPort
call IPC_SerialIn
xor ah, ah
ret
; -----------------------------------------------------------------
; INT 14 function 03 - get serial port status.
; -----------------------------------------------------------------
INT_14_03:
test dx, dx
jnz INT_14_NoPort
call IPC_SerialStatus
cmp al, 00h
mov ax, 6010h
jz INT_14_03_NoData
or ah, 01h
INT_14_03_NoData:
ret
; -----------------------------------------------------------------
; INT 15 - BIOS functions.
; -----------------------------------------------------------------
INT_15:
INT_Debug 15h
stc
sti
retf 2
; -----------------------------------------------------------------
; INT 16 - keyboard functions.
; -----------------------------------------------------------------
INT_16:
INT_Debug 16h
and ah, 0CFh ; Map 1x and 2x functions to 0x
cmp ah, 09h
je INT_16_09
cmp ah, 03h
ja INT_16_Ret
cli
push bp
mov bp, INT_16_Functions
call INT_Dispatch
pop bp
sti
retf 2 ; To retain the ZF flag!
INT_16_09:
xor al, al
INT_16_Ret:
iret
INT_16_Functions:
dw INT_16_00
dw INT_16_01
dw INT_16_02
dw INT_Unimplemented
; -----------------------------------------------------------------
; INT 16 function 00 - read from keyboard buffer.
; -----------------------------------------------------------------
INT_16_00:
call Screen_Interrupt
INT_16_00_Loop:
sti
nop
cli
; Get 6509 status
out 0E8h, al
in al, 21h
out 0E9h, al
test al, 01h
jnz INT_16_00_Loop
call IPC_KbdClear
push bx
mov bx, ax
call IPC_KbdConvert
push ds
push ax
mov ax, Data_Segment
mov ds, ax
test [Data_Boot], byte 80h
jz INT_16_00_NoBoot
; Get key scancode in AL
mov ax, bx
xor ah, ah
call IPC_KbdConvert
; Simulate keypress with INT 09
mov ax, Virtual_Segment
mov ds, ax
pop ax
push ax
mov [V_Port_60], al
int 09h
or [V_Port_60], byte 80h
int 09h
INT_16_00_NoBoot:
pop ax
pop ds
INT_16_00_Ret:
pop bx
ret
; -----------------------------------------------------------------
; INT 16 function 01 - peek into keyboard buffer.
; -----------------------------------------------------------------
INT_16_01:
call Screen_Interrupt
out 0E8h, al
in al, 21h
out 0E9h, al
; Fake INT 09 for Microsoft QBASIC
push ax
push ds
mov ax, Virtual_Segment
mov ds, ax
mov [V_Port_60], byte 0AAh ; Left Shift depressed
int 09h
pop ds
pop ax
test al, 01h
jnz INT_16_NoKey
call IPC_KbdPeek
jmp IPC_KbdConvert
INT_16_NoKey:
xor ax, ax
ret
; -----------------------------------------------------------------
; INT 16 function 02 - get shift key state.
; -----------------------------------------------------------------
INT_16_02:
out 0E8h, al
in al, 21h
out 0E9h, al
mov ah, al
; Store shift key state in BIOS data area for Turbo Pascal 7
INT_16_BIOSFlags:
xor al, al
test ah, 10h
jnz INT_16_BIOSFlags_NoShift
or al, 01h
INT_16_BIOSFlags_NoShift:
test ah, 20h
jnz INT_16_BIOSFlags_NoCtrl
or al, 04h
INT_16_BIOSFlags_NoCtrl:
test ah, 08h
jnz INT_16_BIOSFlags_NoAlt
or al, 08h
INT_16_BIOSFlags_NoAlt:
push bx
push ds
xor bx, bx
mov ds, bx
mov [0417h], al
pop ds
pop bx
mov ah, 02h
ret
; -----------------------------------------------------------------
; INT 17 - printer functions.
; -----------------------------------------------------------------
INT_17:
INT_Debug 17h
cmp ah, 02h
ja INT_17_Ret
push bp
mov bp, INT_17_Functions
call INT_Dispatch
pop bp
INT_17_Ret:
iret
INT_17_Functions:
dw INT_17_00
dw INT_17_01
dw INT_17_02
; -----------------------------------------------------------------
; INT 17 function 00 - output byte to printer.
; -----------------------------------------------------------------
INT_17_00:
call IPC_PrinterOut
ret
; -----------------------------------------------------------------
; INT 17 function 01 - initialize printer (unimplemented).
; -----------------------------------------------------------------
INT_17_01:
ret
; -----------------------------------------------------------------
; INT 17 function 02 - get printer status.
; -----------------------------------------------------------------
INT_17_02:
mov ah, 80h
ret
; -----------------------------------------------------------------
; INT 18 - ROM BASIC.
; -----------------------------------------------------------------
INT_18:
INT_Debug 18h
jmp INT_19_Again
; -----------------------------------------------------------------
; INT 19 - Reboot.
; -----------------------------------------------------------------
INT_19:
INT_Debug 19h
INT_19_Again:
push cs
pop ds
call Output_Line
mov si, INT_19_Banner1
call Output_String
INT_19_Loop:
call INT_16_00
cmp ah, 3Ch ; F2
jz INT_19_Floppy
cmp ah, 3Bh ; F1
jz INT_19_HD
cmp ah, 44h ; F10
jz Config_Modify
cmp ax, 02E03h ; Run/Stop
jz Config_Reset
jmp INT_19_Loop
; Try loading boot sector from hard disk
INT_19_HD:
call Output_Line
mov dx, 0080h
mov ax, 0201h
xor cx, cx
mov es, cx
inc cx
mov bx, 7C00h
call INT_13_02
jc INT_19_Error
cmp [es:7DFEh], word 0AA55h
jne INT_19_NoSystem
mov dl, 80h
jmp INT_19_Found
INT_19_Floppy:
call Output_Line
; Load two first 256-byte sectors from the floppy disk.
xor bx, bx
mov es, bx
mov bp, bx
mov bx, 7C00h
xor dl, dl
mov ax, 0001h
call IPC_SectorAccess
mov bx, 7D00h
mov ax, 0101h
call IPC_SectorAccess
cmp [es:7DFEh], word 0AA55h
jne INT_19_NoSystem
xor dl, dl
INT_19_Found:
push dx
call IPC_Init
; Jump to boot sector code.
call INT_19_Segments
mov si, INT_19_Banner2
call Output_String
mov [es:Data_Boot], byte 80h
pop dx
jmp 0000:7C00h
INT_19_NoSystem:
call INT_19_Segments
mov si, INT_19_Banner3
call Output_String
jmp INT_19_Again
INT_19_Segments:
mov ax, Data_Segment
mov es, ax
push cs
pop ds
ret
INT_19_Error:
call INT_19_Segments
mov si, INT_19_Banner4
call Output_String
jmp INT_19_Again
INT_19_Banner1:
db "Select an option:", 10, 13
db " F1 - Boot from SD card", 10, 13
db " F2 - Boot from floppy disk", 10, 13
db " F10 - Modify configuration", 10, 13
db " Run/Stop - Reset configuration", 10, 13
db 0
INT_19_Banner4:
db "SD card not found, please try again.", 10, 13, 0
INT_19_Banner2:
db "The system is coming up, please wait.", 10, 13, 0
INT_19_Banner3:
db "Insert a system disk and press any key.", 10, 13, 0
; -----------------------------------------------------------------
; INT 1A - Timer functions.
; -----------------------------------------------------------------
INT_1A:
INT_Debug 1Ah
test ah, ah
je INT_1A_00
cmp ah, 01
je INT_1A_01
cmp ah, 02
je INT_1A_02
cmp ah, 03
je INT_1A_03
cmp ah, 04
je INT_1A_04
cmp ah, 05
je INT_1A_05
stc
xor dx, dx
xor cx, cx
retf 2
; -----------------------------------------------------------------
; INT 1A function 00 - get system time.
; -----------------------------------------------------------------
INT_1A_00:
push ds
xor cx, cx
mov ds, cx
mov dx, [046Ch]
mov cx, [046Eh]
xor al, al
pop ds
clc
retf 2
; push ax
; push bx
; call INT_1A_02_Do
; mov al, dh
; call ConvertFromBCD
; mov ah, al ; AH = Seconds
; push ax
; mov al, cl
; call ConvertFromBCD
; mov dl, al ; DL = Minutes
; mov al, ch
; call ConvertFromBCD
; mov dh, al ; DH = Hours
; pop ax
; xor al, al ; AL = Microseconds
; Calculate number of ticks in whole minutes
; mov bx, ax
; mov al, dh
; mov cl, 60
; mul cl
; xor dh, dh
; add ax, dx
; mov cx, 1092 ; Ticks per minute
; mul cx
; push dx
; push ax
; Calculate number of ticks in seconds
; mov al, bh
; mov cl, 10
; mul cl
; xor bh, bh
; add ax, bx
; mov cx, 182
; mul cx
; mov cx, 100
; div cx
; Add them together
; pop cx
; add cx, ax
; pop dx
; xor ax, ax
; adc dx, ax
; pop bx
; pop ax
; xor al, al
; xchg cx, dx
; iret
; -----------------------------------------------------------------
; INT 1A function 01 - set system time.
; -----------------------------------------------------------------
INT_1A_01:
push ax
push ds
xor ax, ax
mov ds, ax
mov [046Ch], dx
mov [046Eh], cx
pop ds
pop ax
clc
retf 2
; push ax
; push bx
; push cx
; push dx
; mov ax, dx
; mov dx, cx
; Calculate hour and minute
; mov cx, 1092 ; Ticks per minute
; div cx
; mov bx, dx
; mov cl, 60
; div cl
; xchg al, ah
; Calculate number of seconds
; xchg ax, bx
; xor dx, dx
; mov cx, 50
; mul cx
; mov cx, 91
; div cx
; mov cl, 10
; div cl
; xchg al, ah
; mov dx, bx
; push ax
; mov al, dh
; call ConvertToBCD
; mov ch, al
; mov al, dl
; call ConvertToBCD
; mov cl, al
; pop ax
; mov al, ah
; call ConvertToBCD
; mov dh, al
; call INT_1A_03_Do
; pop dx
; pop cx
; pop bx
; pop ax
; iret
; -----------------------------------------------------------------
; INT 1A function 02 - get RTC time.
; -----------------------------------------------------------------
INT_1A_02:
call INT_1A_02_Do
retf 2
INT_1A_02_Do:
push ax
call I2C_Start
; RTC adress + write flag
mov al, 0D0h
call I2C_Send
jnc INT_1A_02_Do2
call I2C_Stop
pop ax
stc
ret
INT_1A_02_Do2:
; Read start address
mov al, 00h
call I2C_Send
call I2C_Start
; RTC adress + read flag
mov al, 0D1h
call I2C_Send
; Read address 00 (seconds)
clc
call I2C_Receive
and al, 7Fh
mov dh, al