mirror of
https://github.com/bobbimanners/Applecorn.git
synced 2024-06-24 02:29:32 +00:00
193 lines
5.5 KiB
ArmAsm
193 lines
5.5 KiB
ArmAsm
* BUFFER.S
|
|
* Buffer handling code, called by INSV, REMV, CNPV
|
|
|
|
* Location and sizes of buffers
|
|
* -----------------------------
|
|
BUF4 EQU $0340
|
|
BUF4SZ EQU 16
|
|
BUF5 EQU $0350
|
|
BUF5SZ EQU 16
|
|
BUF6 EQU $0360
|
|
BUF6SZ EQU 16
|
|
BUF7 EQU $0370
|
|
BUF7SZ EQU 16
|
|
BUF3 EQU $0380
|
|
BUF3SZ EQU 64
|
|
BUFBASE EQU $03C0 ; Base of buffer workspace
|
|
BUF0 EQU $03E0
|
|
BUF0SZ EQU 32
|
|
BUF2 EQU $0C00
|
|
BUF2SZ EQU 192
|
|
BUF8 EQU $0CC0
|
|
BUF8SZ EQU 64
|
|
BUF1 EQU $0D00
|
|
BUF1SZ EQU 256
|
|
|
|
|
|
* The buffers are arranged so that an offset of &FF is the last entry, and
|
|
* incrementing to &00 passes the end of the buffer. A buffer is empty when
|
|
* BUFINP=BUFOUT, and is full when BUFINP+1=BUFOUT.
|
|
|
|
* BUFFER ADDRESS LOW BYTE LOOKUP TABLE
|
|
* ------------------------------------
|
|
* start+len
|
|
BUFLO DB (BUF0 + BUF0SZ - 256) AND 255 ; keyboard
|
|
DB (BUF1 + BUF1SZ - 256) AND 255 ; serial input
|
|
DB (BUF2 + BUF2SZ - 256) AND 255 ; serial output
|
|
DB (BUF3 + BUF3SZ - 256) AND 255 ; printer
|
|
DB (BUF4 + BUF4SZ - 256) AND 255 ; sound 0
|
|
DB (BUF5 + BUF5SZ - 256) AND 255 ; sound 1
|
|
DB (BUF6 + BUF6SZ - 256) AND 255 ; sound 2
|
|
DB (BUF7 + BUF7SZ - 256) AND 255 ; sound 3
|
|
DB (BUF8 + BUF8SZ - 256) AND 255 ; speech
|
|
|
|
* BUFFER ADDRESS HIGH BYTE LOOKUP TABLE
|
|
* -------------------------------------
|
|
* start+len
|
|
BUFHI DB (BUF0 + BUF0SZ - 256) DIV 256 ; keyboard
|
|
DB (BUF1 + BUF1SZ - 256) DIV 256 ; serial input
|
|
DB (BUF2 + BUF2SZ - 256) DIV 256 ; serial output
|
|
DB (BUF3 + BUF3SZ - 256) DIV 256 ; printer
|
|
DB (BUF4 + BUF4SZ - 256) DIV 256 ; sound 0
|
|
DB (BUF5 + BUF5SZ - 256) DIV 256 ; sound 1
|
|
DB (BUF6 + BUF6SZ - 256) DIV 256 ; sound 2
|
|
DB (BUF7 + BUF7SZ - 256) DIV 256 ; sound 3
|
|
DB (BUF8 + BUF8SZ - 256) DIV 256 ; speech
|
|
|
|
* BUFFER START ADDRESS OFFSET
|
|
* ---------------------------
|
|
* len
|
|
BUFOFF DB 256-BUF0SZ
|
|
DB 256-BUF1SZ
|
|
DB 256-BUF2SZ
|
|
DB 256-BUF3SZ
|
|
DB 256-BUF4SZ
|
|
DB 256-BUF5SZ
|
|
DB 256-BUF6SZ
|
|
DB 256-BUF7SZ
|
|
DB 256-BUF8SZ
|
|
|
|
BUFNUM EQU BUFHI-BUFLO ; Number of buffers
|
|
BUFFLG EQU BUFBASE+0*BUFNUM ; Buffer flags
|
|
BUFINP EQU BUFBASE+1*BUFNUM ; Input pointers
|
|
BUFOUT EQU BUFBASE+2*BUFNUM ; Output pointers
|
|
|
|
|
|
* Get buffer base address
|
|
* -----------------------
|
|
* On entry, X=buffer number (not checked)
|
|
* On exit, (OSINTWS)=>buffer base
|
|
BUFADDR LDA BUFLO,X
|
|
STA OSINTWS+0 ; Get buffer base address low
|
|
LDA BUFHI,X
|
|
STA OSINTWS+1 ; Get buffer base address high
|
|
RTS
|
|
|
|
|
|
* REMV buffer remove
|
|
* ==================
|
|
* On entry, X =buffer number
|
|
* VS=examine buffer
|
|
* VC=remove from buffer
|
|
* On exit, X =preserved
|
|
* CS=buffer empty
|
|
* A,Y corrupted
|
|
* CC=buffer not empty
|
|
* A=Y=byte from buffer
|
|
* If called to remove from buffer, pointers updated
|
|
*
|
|
BUFREM PHP ; Save flags
|
|
SEI ; Disable IRQs
|
|
CPX #BUFNUM ; Valid buffer number?
|
|
BCS BUFFAIL ; No, return 'empty'
|
|
LDA BUFOUT,X ; Get output pointer for buffer X
|
|
CMP BUFINP,X ; Compare it to input pointer
|
|
BEQ BUFFAIL ; Equal, so buffer is empty
|
|
TAY ; Y=output pointer
|
|
JSR BUFADDR ; Get buffer base address
|
|
LDA (OSINTWS),Y ; Get byte from buffer
|
|
BVS BUFREM2 ; If VS, just examine buffer, return
|
|
INY ; Otherwise, update buffer pointer
|
|
BNE BUFREM1 ; Not zero, not reached end of buffer
|
|
LDY BUFOFF,X ; Get offset to start of buffer
|
|
BUFREM1 STY BUFOUT,X ; Update the buffer output pointer
|
|
BUFREM2 TAY ; Return A=Y=byte from buffer
|
|
PLP ; Restore IRQs
|
|
CLC ; CLC=success
|
|
RTS
|
|
|
|
|
|
* INSV buffer insert
|
|
* ==================
|
|
* On entry, X =buffer number
|
|
* A =byte to be inserted
|
|
* On exit, X =preserved
|
|
* A =preserved
|
|
* Y =corrupted
|
|
* CS=buffer full, couldn't insert
|
|
* CC=buffer wasn't full, insertion successful
|
|
*
|
|
BUFINS PHP ; Save flags
|
|
SEI ; Disable IRQs
|
|
CPX #BUFNUM ; Valid buffer number?
|
|
BCS BUFINS2 ; No, sink it and return 'ok'
|
|
PHA ; Save A
|
|
LDY BUFINP,X ; Get buffer input pointer
|
|
INY ; Otherwise, update buffer pointer
|
|
BNE BUFINS1 ; Not zero, not reached end of buffer
|
|
LDY BUFOFF,X ; Get offset to start of buffer
|
|
BUFINS1 TYA ; A=updated input pointer
|
|
CMP BUFOUT,X ; Compare with output pointer
|
|
BEQ BUFINS4 ; Same, buffer is full, exit with 'failed'
|
|
LDY BUFINP,X ; Get unupdated input pointer back
|
|
STA BUFINP,X ; Store updated input pointer
|
|
JSR BUFADDR ; Get buffer base address
|
|
PLA ; Get the byte back
|
|
STA (OSINTWS),Y ; And store it in buffer
|
|
BUFINS2 PLP ; Restore IRQs
|
|
CLC ; CLC=success
|
|
RTS
|
|
|
|
BUFINS4 PLA ; Restore A
|
|
BUFFAIL PLP ; Restore IRQs
|
|
SEC ; SEC=failed
|
|
RTS
|
|
|
|
|
|
* CNPV count/purge buffer
|
|
* =======================
|
|
* On entry, X =buffer number
|
|
* VC=purge (clear) buffer
|
|
* VS=count buffer
|
|
* CC=count used space
|
|
* CS=count free space
|
|
* On exit, XY=size counted
|
|
* A =corrupted
|
|
*
|
|
BUFCNP CPX #BUFNUM ; Valid buffer number?
|
|
BCS BUFCNP1 ; No, ignore it
|
|
BVC BUFCNT1 ; VS, count buffer
|
|
LDA BUFOUT,X ; Set input=output, empty buffer
|
|
STA BUFINP,X
|
|
BUFCNP1 BVS BUFCNT5 ; Purged, exit
|
|
LDX #$00
|
|
BEQ BUFCNT4 ; Count, return zero
|
|
|
|
BUFCNT1 PHP ; Save flags
|
|
SEI ; Disable IRQs
|
|
SEC ; Prepare for SBC
|
|
LDA BUFOUT,X ; Get output pointer
|
|
SBC BUFINP,X ; Subtract input pointer
|
|
BCS BUFCNT2 ; No overflow, use it
|
|
SEC ; Prepare for SBC
|
|
SBC BUFOFF,X ; Subtract buffer start offset
|
|
BUFCNT2 PLP ; Get flags back, also restore IRQs
|
|
BCC BUFCNT3 ; CLC, exit with size counted
|
|
CLC ; Prepare for ADC
|
|
ADC BUFOFF,X ; Add buffer offset to get NEG(bytes free)
|
|
EOR #&FF ; Invert it to get free space
|
|
BUFCNT3 TAX ; YX=count
|
|
BUFCNT4 LDY #&00 ; All our buffers are <256 bytes
|
|
BUFCNT5 RTS
|
|
|