mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-22 01:31:33 +00:00
176 lines
5.5 KiB
Plaintext
176 lines
5.5 KiB
Plaintext
; Vera Memory Access Assembly Language Routines for C02
|
|
; Requires External Routines RESRXY, SETDST, and SETSRC
|
|
; and External Variables TEMP0 and TEMP1
|
|
|
|
;Vera External Registers
|
|
;$9F20 Address LSB
|
|
;$9F21 Address MSB
|
|
;$9F22 Auto-Increment and Address Bank
|
|
;$9F23 Data Port 0
|
|
;$9F24 Data Port 1
|
|
;$9F25 Control Register
|
|
;$9F26 Interrupt Enable
|
|
;$9F27 Interrupt Status
|
|
|
|
|
|
;asladr() - Shift Vera Address Left`
|
|
;Args: X = Number of Bits to Shift
|
|
;Updates: TEMP0 = Bank
|
|
; TEMP1 = Address LSB
|
|
; TEMP3 = Address MSB
|
|
;Returns: A = Bank
|
|
; Y,X = Address
|
|
ASLADR: ASL TEMP1 ;Shift LSB Left
|
|
ROL TEMP2 ;Rotate Carry Left into MSB
|
|
ROL TEMP0 ;Rotate Carry Left into LSB
|
|
DEX ;Decrement Shift Count
|
|
BNE ASLADR ;and Loop if Not Zero
|
|
JMP RESREG ;Return Bank, MSB, LSB
|
|
|
|
;getadr() - Get Vera Address
|
|
;Args: A = Bank + Auto-Increment
|
|
; Y,X = Address
|
|
GETADR: LDX $9F20 ;Store Address LSB
|
|
LDY $9F21 ;Store Address MSB
|
|
LDA $9F22 ;Store Bank & Auto-Increment
|
|
RTS
|
|
|
|
;getvrg(&addr) - Read Vera Internal Register
|
|
;Args: Y,X = Address
|
|
;Returns: A = Mode
|
|
; X = Current Data Port
|
|
GETVRG: LDA #$0F ;Set Bank to Registers
|
|
;and Execute GETBYT
|
|
;getbyt(&addr);
|
|
;Args: A = Bank
|
|
; Y,X = Address
|
|
;Affects: Y
|
|
;Returns: A = Contents of Memory
|
|
; X = Current Data Port
|
|
GETBYT: JSR SETADR ;Set Vera Address
|
|
LDX $9F25 ;Get Current Data Port
|
|
LDA $9F23,X ;Read LSB from Data Port
|
|
RTS
|
|
|
|
;getmem(count, &addr) - Read Array From Vera Memory
|
|
;Args: A = Number of Bytes to Read
|
|
; Y,X = Address of Array to Read Into
|
|
;Requires: setadr()
|
|
;Sets: DSTLO,DSTHI = Address of Array
|
|
; TEMP0 = Number of Bytes to Read
|
|
;Affects: A
|
|
;Returns: Y = Number of Bytes Read
|
|
; X = Current Data Port
|
|
GETMEM: JSR SETDST ;Save Destination Address
|
|
GETMEA: STA TEMP0 ;Save Number of Bytes
|
|
LDY #0 ;Initialize Counter
|
|
LDX $9F25 ;Get Current Data Port
|
|
GETMEL: LDA $9F23,X ;Read Byte from Data Port
|
|
STA (DSTLO),Y ;Store in Memory
|
|
INY ;Increment Counter
|
|
CPY TEMP0 ;If Limit Not Reached
|
|
BNE GETMEL ; Loop
|
|
|
|
;getvri(addr); Read Vera Register Pair
|
|
;Args: Y,X = Address
|
|
;Returns: A,X = Integer LSB
|
|
; Y = Integer LSB
|
|
GETVRI: LDA #$0F ;Set Bank to Registers
|
|
|
|
;getint(addr); Read Integer from Vera Memory
|
|
;Args: A = Bank
|
|
; Y,X = Address
|
|
;Returns: A,X = Integer LSB
|
|
; Y = Integer LSB
|
|
GETINT: AND #$0F ;Set Auto-Increment to 1
|
|
ORA #$10
|
|
JSR SETADR ;Set Vera Address
|
|
LDX $9F25 ;Get Current Data Port
|
|
LDA $9F23,X ;Read LSB from Data Port
|
|
LDY $9F23,X ;Read MSB Data Port
|
|
TAX ;Copy LSB to X
|
|
RTS
|
|
|
|
;regadr(opts,addr) - Set Vera Address to Internal Register
|
|
;Args: Y,X = Register Address
|
|
;Returns: A= Bank + Auto-Increment
|
|
REGADR: LDA #$1F ;Set Bank and Auto-Increment
|
|
|
|
;setadr(opts,addr) - Set Vera Address
|
|
;Args: A = Bank + Auto-Increment
|
|
; Y,X = Address
|
|
SETADR: STX $9F20 ;Store Address LSB
|
|
STY $9F21 ;Store Address MSB
|
|
STA $9F22 ;Store Bank & Auto-Increment
|
|
RTS
|
|
|
|
;setreg(addr) - Set Register
|
|
;Args: A = Value to Write
|
|
; Y,X = Address
|
|
;Sets: TEMP0 = Value to Write
|
|
;Returns: A = Value Written
|
|
; X = Current Data Port
|
|
SETREG: STA TEMP0 ;Save Value to Write
|
|
SETREH: LDA #$0F ;Set Bank, Auto-Increment
|
|
|
|
;setbyt(addr) - Write Byte to Vera Memory
|
|
;Args: A = Bank
|
|
; Y,X = Address
|
|
;Uses: TEMP0 = Value to Write
|
|
;Returns: A = Value Written
|
|
; X = Current Data Port
|
|
SETBYT: JSR SETADR ;Set Vera Address
|
|
LDA TEMP0 ;Retrieve Value to Write
|
|
LDX $9F25 ;Get Current Data Port
|
|
STA $9F23,X ;Write Value to Data Port
|
|
RTS
|
|
|
|
;setrei(addr) - Set Vera Register to Integer
|
|
;Args: Y,X = Address
|
|
;Uses: TEMP1,TEMP2 = Integer Value
|
|
;Affects: A,Y
|
|
;Returns: X = Current Data Port
|
|
SETREI: LDA #$0F ;Set Bank to Registers
|
|
|
|
;setina(addr) - Write Integer to Vera Address
|
|
;Args: A = Bank
|
|
; Y,X = Address
|
|
;Uses: TEMP1,TEMP2 = Integer Value
|
|
;Affects: A,Y
|
|
;Returns: X = Current Data Port
|
|
SETINA: ORA #$10 ;Set Auto-Increment to 1
|
|
JSR SETADR ;Set Vera Address
|
|
JSR RESRXY ;Restore Integer into Y,X
|
|
|
|
;setint(addr) - Write Integer to Vera Memory
|
|
;Args: Y,X = Integer to Write
|
|
;Requires: setadr();
|
|
;Affects: A,Y
|
|
;Returns: X = Current Data Port
|
|
SETINT: TXA ;Copy LSB to Accumlator
|
|
LDX $9F25 ;Get Current Data Port
|
|
STA $9F23,X ;Write to Data Port
|
|
TYA ;Copy MSB to Accumlator
|
|
STA $9F23,X ;Write to Data Port
|
|
RTS
|
|
|
|
;setmem(count, &addr) - Write Array to Vera Memory
|
|
;Args: A = Number of Bytes to Write
|
|
; Y,X = Address of Array to Write From
|
|
;Requires: setadr()
|
|
;Sets: SRCLO,SRCHI = Address of Array
|
|
; TEMP0 = Number of Bytes to Write
|
|
;Affects: A
|
|
;Returns: Y = Number of Bytes Written
|
|
; X = Current Data Port
|
|
SETMEM: STA TEMP0 ;Save Number of Bytes
|
|
JSR SETSRC ;Save Destination Address
|
|
SETMEA: LDX $9F25 ;Get Current Data Port
|
|
LDY #0 ;Initialize Counter
|
|
SETMEL: LDA (SRCLO),Y ;Read Byte from Array
|
|
STA $9F23,X ;Write Byte to Data Port
|
|
INY ;Increment Counter
|
|
CPY TEMP0 ;If Limit Not Reached
|
|
BNE SETMEL ; Loop
|
|
RTS
|