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Working on the serial driver
git-svn-id: svn://svn.cc65.org/cc65/trunk@2414 b7a2c559-68d2-44c3-8de9-860c34a00d81
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cuz
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@ -41,11 +41,10 @@
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.word INSTALL
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.word UNINSTALL
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.word PARAMS
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.word OPEN
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.word CLOSE
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.word GET
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.word PUT
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.word PAUSE
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.word UNPAUSE
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.word STATUS
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.word IOCTL
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@ -64,16 +63,18 @@ ACIA_CLOCK = ACIA+7 ; Turbo232 external baud-rate generator
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; Global variables
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;
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; We reuse the RS232 zero page variables for the driver, since the ROM
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; routines cannot be used together with this driver.
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RecvHead = $B5 ; Head of receive buffer
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RecvTail = $BD ; Tail of receive buffer
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RecvFreeCnt = $F7 ; Number of bytes in receive buffer
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SendHead = $F8 ; Head of send buffer
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SendTail = $F9 ; Tail of send buffer
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SendFreeCnt = $FA ; Number of bytes free in send buffer
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.bss
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Stopped: .res 1 ; Flow-stopped flag
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RtsOff: .res 1 ;
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RecvHead: .res 1 ; Head of receive buffer
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RecvTail: .res 1 ; Tail of receive buffer
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RecvFreeCnt: .res 1 ; Number of bytes in receive buffer
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SendHead: .res 1 ; Head of send buffer
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SendTail: .res 1 ; Tail of send buffer
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SendFreeCnt: .res 1 ; Number of bytes free in send buffer
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BaudCode: .res 1 ; Current baud in effect
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; Send and receive buffers: 256 bytes each
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RecvBuf: .res 256
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@ -126,31 +127,6 @@ ParityTable:
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.byte $A0 ; SER_PAR_MARK
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.byte $E0 ; SER_PAR_SPACE
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; Delay times: 32 byte-receive times in milliseconds, or 100 max.
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; Formula = 320,000 / baud. Invalid values do contain $FF.
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PauseTimes:
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.byte $FF ; SER_BAUD_45_5
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.byte $FF ; SER_BAUD_50
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.byte $FF ; SER_BAUD_75
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.byte $FF ; SER_BAUD_110
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.byte $FF ; SER_BAUD_134_5
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.byte $FF ; SER_BAUD_150
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.byte 100 ; SER_BAUD_300
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.byte 100 ; SER_BAUD_600
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.byte 100 ; SER_BAUD_1200
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.byte $FF ; SER_BAUD_1800
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.byte 100 ; SER_BAUD_2400
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.byte $FF ; SER_BAUD_3600
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.byte 67 ; SER_BAUD_4800
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.byte $FF ; SER_BAUD_7200
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.byte 34 ; SER_BAUD_9600
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.byte 17 ; SER_BAUD_19200
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.byte 9 ; SER_BAUD_38400
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.byte $FF ; SER_BAUD_57600
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.byte $FF ; SER_BAUD_115200
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.byte $FF ; SER_BAUD_230400
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.code
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;----------------------------------------------------------------------------
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@ -165,19 +141,7 @@ INSTALL:
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lda #%00001010
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sta ACIA_CMD
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; Initialize buffers & control
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@L4: ldx #0
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stx RecvHead
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stx SendHead
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stx RecvTail
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stx SendTail
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stx Stopped
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dex ; X = 255
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stx RecvFreeCnt
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stx SendFreeCnt
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; Set up nmi's
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; Set up the nmi vector
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lda NMIVec
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ldy NMIVec+1
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@ -215,15 +179,19 @@ UNINSTALL:
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; PARAMS routine. A pointer to a ser_params structure is passed in ptr1.
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; Must return an SER_ERR_xx code in a/x.
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PARAMS:
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OPEN:
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; First, check if the handshake setting is valid
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; Check if the handshake setting is valid
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ldy #SER_PARAMS_HANDSHAKE ; Handshake
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lda (ptr1),y
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cmp #SER_HS_HW ; This is all we support
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bne InvParam
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; Initialize buffers
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jsr InitBuffers
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; Set the value for the control register, which contains stop bits, word
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; length and the baud rate.
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@ -233,7 +201,6 @@ PARAMS:
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lda BaudTable,y ; Get 6551 value
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bmi InvBaud ; Branch if rate not supported
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sta tmp1
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sty BaudCode ; Remember baud rate index
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ldy #SER_PARAMS_DATABITS ; Databits
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lda (ptr1),y
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@ -282,17 +249,35 @@ InvBaud:
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ldx #>SER_ERR_BAUD_UNAVAIL
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rts
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;----------------------------------------------------------------------------
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; CLOSE: Close the port, disable interrupts and flush the buffer. Called
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; without parameters. Must return an error code in a/x.
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;
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CLOSE:
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; Stop interrupts, drop DTR
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lda #%00001010
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sta ACIA_CMD
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; Initalize buffers. Returns zero in a
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jsr InitBuffers
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; Return OK
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lda #<SER_ERR_OK
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tax ; A is zero
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rts
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;----------------------------------------------------------------------------
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; GET: Will fetch a character from the receive buffer and store it into the
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; variable pointer to by ptr1. If no data is available, SER_ERR_NO_DATA is
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; return.
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;
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GET:
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; Check for bytes to send
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ldx SendFreeCnt
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GET: ldx SendFreeCnt ; Send data if necessary
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inx ; X == $FF?
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beq @L1
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lda #$00
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@ -364,69 +349,15 @@ PUT:
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tax
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rts
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;----------------------------------------------------------------------------
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; PAUSE: Assert flow control and disable interrupts.
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; Must return an error code in a/x.
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;
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PAUSE:
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; Assert flow control
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lda RtsOff
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sta Stopped
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sta ACIA_CMD
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; Delay for flow stop to be received
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ldx BaudCode
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ldy PauseTimes,x
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jsr DelayMs
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; Stop rx interrupts
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lda RtsOff
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ora #%00000010 ; Disable interrupts
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sta ACIA_CMD
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lda #<SER_ERR_OK
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tax
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rts
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;----------------------------------------------------------------------------
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; UNPAUSE: Re-enable interrupts and release flow control.
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; Must return an error code in a/x.
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;
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UNPAUSE:
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; Re-enable rx interrupts & release flow control
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@L1: lda #$00
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sta Stopped
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lda RtsOff
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ora #%00001000
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sta ACIA_CMD
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; Poll for stalled char & exit
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jsr PollReceive
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lda #<SER_ERR_OK
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tax
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rts
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;----------------------------------------------------------------------------
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; STATUS: Return the status in the variable pointed to by ptr1.
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; Must return an error code in a/x.
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;
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STATUS:
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lda ACIA_STATUS
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ldy #0
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sta (ptr1),y
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jsr PollReceive ; bug-recovery hack
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tya ; SER_ERR_OK
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tax
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STATUS: lda ACIA_STATUS
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ldx #0
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sta (ptr1,x)
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txa ; SER_ERR_OK
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rts
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;----------------------------------------------------------------------------
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@ -435,8 +366,7 @@ STATUS:
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; Must return an error code in a/x.
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;
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IOCTL:
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lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
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IOCTL: lda #<SER_ERR_INV_IOCTL ; We don't support ioclts for now
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ldx #>SER_ERR_INV_IOCTL
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rts
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@ -519,57 +449,19 @@ NmiHandler:
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.endproc
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;----------------------------------------------------------------------------
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;
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; PollReceive - poll for rx char
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; This function is useful in odd cases where the 6551 has a character in
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; it but it fails to raise an NMI. It might be edge-triggering conditions?
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; Actually, I'm not entirely sure that this condition can still arrise, but
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; calling this function does no harm.
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;
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.proc PollReceive
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lda #$08
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and ACIA_STATUS
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beq @L9
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and ACIA_STATUS
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beq @L9
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lda ACIA_DATA
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ldx RecvFreeCnt
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beq @L9
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ldx RecvTail
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sta RecvBuf,x
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inc RecvTail
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dec RecvFreeCnt
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@L9: rts
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.endproc
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;----------------------------------------------------------------------------
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;
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; DelayMs : delay for given number of milliseconds
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; This implementation isn't very rigerous; it merely delays for the
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; approximate number of clock cycles for the processor speed.
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; Algorithm:
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; repeat for number of milliseconds:
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; delay for 1017 clock cycles
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;
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.proc DelayMs ;( .A=milliseconds )
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@L1: ldx #203 ;(2)
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@L2: dex ;(2)
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bne @L2 ;(3) // 1017 cycles
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dey
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bne @L1
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rts
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.endproc
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.end
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; Initialize buffers
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InitBuffers:
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ldx #0
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stx Stopped
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stx RecvHead
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stx RecvTail
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stx SendHead
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stx SendTail
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dex ; X = 255
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stx RecvFreeCnt
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stx SendFreeCnt
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rts
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