mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-19 12:32:08 +00:00
237 lines
7.4 KiB
Plaintext
237 lines
7.4 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
|
|
BRA RESREG ;Return Bank, MSB, LSB
|
|
|
|
;chkadr(opts,addr) - Check Vera Address
|
|
;Args: A = Bank + Auto-Increment
|
|
; Y,X = Address
|
|
;Returns: A = $00 - Address is Invalid
|
|
; $FF - Address is Valid
|
|
CHKADR: AND #$0F ;Isolate Bank
|
|
CMP #$0F ;If Registers
|
|
BEQ GETVRT ; Return True
|
|
CMP #$02 ;Else If <2
|
|
BCS GETVRT ; Return True
|
|
LDA #$0 ;Else Return False
|
|
RTS
|
|
|
|
;clrmem(count) - Write Array to Vera Memory
|
|
;Args: A = Number of Bytes to Clear
|
|
;Returns: A,Y = 0
|
|
; X = Current Data Port
|
|
CLRMEM: TAY ;Copy Number of Bytes to Y
|
|
LDA #0 ;Set Write Value to Zero
|
|
|
|
;filmem(byte, count) - Fill Vera Memory with Byte
|
|
;Args: A = Byte to Fill Memory With
|
|
; Y = Number of Bytes to Fill
|
|
;Returns: Y = 0
|
|
; X = Current Data Port
|
|
FILMEM LDX $9F25 ;Get Current Data Port
|
|
FILMEL: STA $9F23,X ;Write Byte to Data Port
|
|
DEY ;Decrement Counter
|
|
BNE FILMEL ;If Not Zero Loop
|
|
RTS
|
|
|
|
;getadr() - Get Vera Address
|
|
;Args: A = Bank + Auto-Increment
|
|
; Y,X = Address
|
|
GETADR: LDX $9F20 ;Read Address LSB
|
|
LDY $9F21 ;Read Address MSB
|
|
LDA $9F22 ;Read Bank & Auto-Increment
|
|
RTS
|
|
|
|
;getvrb(&addr) - Get Vera Register Bit Status
|
|
;Args: A = Bit Mask
|
|
; Y,X = Address
|
|
;Returns: A = Mode
|
|
; X = Current Data Port
|
|
GETVRB: STA TEMP0 ;Save Bit Mask
|
|
JSR GETVRG ;Read Register
|
|
AND TEMP0 ;Mask Register Bit
|
|
BEQ GETVRX ;If Set
|
|
GETVRT: LDA #$FF ; Return TRUE
|
|
GETVRX: RTS ;Else Return FALSE
|
|
|
|
;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
|
|
TYA ;Return Count
|
|
RTS
|
|
|
|
;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(addr) - Set Vera Address to Internal Register
|
|
;Args: Y,X = Register Address
|
|
;Returns: A = Bank | Auto-Increment
|
|
REGADR: LDA #$0F ;Set Bank and Auto-Increment
|
|
|
|
;setadi(bank,addr) - Set Vera Address with Auto-Increment
|
|
;Args: A = Bank
|
|
; Y,X = Address
|
|
SETADI: ORA #$10 ;Set Auto-Increment to 1
|
|
|
|
;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
|
|
|
|
;setvrb(bits, &addr) - Set Vera Register Bits
|
|
;Args: A = Bit Pattern
|
|
; Y,X = Address
|
|
;Uses: TEMP0 = Bit Mask
|
|
;Sets: TEMP1 = Bit Pattern
|
|
;Affects: A,Y,X
|
|
SETVRB: STA TEMP1 ;Save Bit Pattern
|
|
JSR GETVRG ;Read Register
|
|
AND TEMP0 ;Mask Result
|
|
ORA TEMP1 ;Set Bits
|
|
BRA SETBYN ;Write Back to Register
|
|
|
|
;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
|
|
SETBYN: 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
|
|
;Returns: A,Y = Number of Bytes Written
|
|
; X = Current Data Port
|
|
SETMEM: JSR SETSRC ;Save Source Address
|
|
SETMET: STA TEMP0 ;Save Number of Bytes
|
|
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
|
|
TYA ;Return Count
|
|
RTS
|