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Tried interrupts with IM 2

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Alexander Noack
2020-04-20 22:58:10 +02:00
parent 638432bb88
commit 7b8eb293fa
1 changed files with 66 additions and 14 deletions
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80
src/test/int_tab.asm
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@@ -1,15 +1,67 @@
;;Tests all interrupt vectors to find which interrupt value is used querying the Keyboard in IM2 ;;Tests all interrupt vectors to find which interrupt value is used querying the Keyboard in IM2
ORG 100H ;Tell the assembler to start at addr 0x100 ORG 100H ;Start at address 0x100
START: IM 2 ;Set interrupt mode 2 ;;setup interrupt vector table. Vector itself will be at 0x2020
LD HL,GREET ;Load the start addr. of the banner DI ;disable interrupts
LD B,16H ;Set the length of the banner text IM 2 ;set interrupt mode 2
LD DE,0H ;Place curser in the top left LD A,03H ;Load the most significant byte of
CALL 84CDH ;Call system str_out LD I,A ;the vector table address to I
LD A,INTTBL/256;Load the vectors for the interrupt table LD HL,0300H ;Start address of the interrupt vector table
LD I,A ;Load the interrupt table to I LD E,L ;Fills the LSB to E
EI ;Make sure interrupt are allowed LD D,H ;and the MSB to D
LOOP: HALT ;Halt the CPU and wait for interrupts INC DE ;increase DE
JR LOOP ;Stay in the loop LD (HL),02H ;Load half of the vector to (HL)
RET ;Return to original caller LD BC,0100H ;257, because of the case where 8-bit vector is 0xFF
GREET: DB 'Test for keyboard int.' LDIR ;walk over the following bytes
END EI ;reenable interrupts
LD HL,GREET ;Load the start of a banner
LD B,15H ;The length of the string
LD DE,0H ;start in the topleft corner
CALL 84CDH ;Call str_out
MLOOP: HALT ;Stop and wait for interrupts
POP AF ;Get the result of the interrupt from the stack
CP 51H ;Checks if the pressed key was "ON/Break"
RET Z ;If the key was "ON" end the program.
LD HL,BUF ;Load the buffer addess
CALL BTOHEX ;Convert the byte in A into a HEX-string and store it at BUF
LD B,2 ;Set the length of BUF
LD DE,15H ;Position cursor in row 0, col 22
CALL 84CDH ;Print the Keycode
JR MLOOP ;Stay in the loop
RET
;;Convert the contents of A into a hex-string and stores the result in the buffer pointed in HL
BTOHEX: PUSH AF ;Store A onto the stack for later use
LD B,4 ;Init a loop for shifting the register
LP1: SRL A ;Shift the MSN down to the least significant Nibble
DJNZ LP1 ;Shift again, until all 4 bits where shifted.
CALL HEXDGT ;Converts the LSN to hex
INC HL ;Point HL to the next byte in buffer
POP AF ;Retrieve the original A
AND 0FH ;Cut the first digit of the hex no.
CALL HEXDGT ;Call HEXDIGIT again for the second digit.
LD HL,BUF ;Restore the buffer address
RET
;;Converts the least significant nibble in A into a ASCII hex-digit and stores the result
HEXDGT: CP 0AH ;Check if the number is smaller than 10
JR C,SKIP ;Skip the next instruction, if it is
ADD A,07H ;If the value is >10, we need to skip the chars between '9' and 'A'
SKIP: ADD A,30H ;Converts the number into its ASCII digit
LD (HL),A ;Store the digit in the correct location.
RET
GREET: DB 'Test keyboard input: '
BUF: DS 2 ;Define a 2 byte buffer to store the keycode in ASCII
ORG 0202H ;Start address of the interrupt handler
DI ;turn off the interrupts
EX AF,AF' ;store the AF register
EXX ;store the register states
IN A,(10H) ;read interrupt reasons from I/O port
SRA A ;test for bit 0 set
JR NC,ENDI ;End the routine, of the reason for interrupt was not the keyboard
CALL 8881H ;Check the pressed button
PUSH AF ;The keycode is in A, push that to the stack as result.
ENDI: EXX ;restore the register states
EX AF,AF' ;restore AF register
EI ;enable interrupts
RETI ;return
ORG 0300H ;start of the vector table
DS 0100H ;reserve 256 bytes
END ;End of memory