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WeeGUI/applesoft.s

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;
; applesoft.s
; Applesoft API via the & extension point
;
; Created by Quinn Dunki on 8/15/14.
; Copyright (c) 2014 One Girl, One Laptop Productions. All rights reserved.
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Applesoft ROM entry points and constants
;
WG_AMPVECTOR = $03f5
CHRGET = $00b1 ; Advances text point and gets character in A
CHRGOT = $00b7 ; Returns character at text pointer in A
SYNCHR = $dec0 ; Validates current character is what's in A
TXTPTR = $00b8 ; (and $b9) ; Current location in BASIC listing
ERROR = $d412 ; Reports error in X
CHKCOM = $debe ; Validates current character is a ',', then gets it
GETBYT = $e6f8 ; Gets an integer at text pointer, stores in X
GETNUM = $e746 ; Gets an 8-bit, stores it X, skips past a comma
ERR_UNDEFINEDFUNC = 224
ERR_SYNTAX = 16
ERR_ENDOFDATA = 5
ERR_TOOLONG = 176
MAXCMDLEN = 14
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGInitApplesoft
; Sets up Applesoft API
;
WGInitApplesoft:
pha
lda #$4c ; Patch in our jump vector for &
sta WG_AMPVECTOR
lda #<WGAmpersand
sta WG_AMPVECTOR+1
lda #>WGAmpersand
sta WG_AMPVECTOR+2
pla
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersand
; The entry point from Applesoft. Applesoft text pointer
; will be positioned two after the '&', and accumulator will
; contain first character after the '&'
; Side effects: Clobbers S0
;
WGAmpersand:
sta SCRATCH0
SAVE_AXY
SAVE_ZPP
ldy #0
ldx SCRATCH0
WGAmpersand_parseLoop:
txa
beq WGAmpersand_matchStart ; Check for end-of-statement (CHRGET handles : and EOL)
cmp #'('
beq WGAmpersand_matchStart
sta WGAmpersandCommandBuffer,y
jsr CHRGET
tax
iny
cpy #MAXCMDLEN
bne WGAmpersand_parseLoop
WGAmpersand_parseFail:
ldx #ERR_SYNTAX
jsr ERROR
bra WGAmpersand_done
WGAmpersand_matchStart:
lda #0
sta WGAmpersandCommandBuffer,y ; Null terminate the buffer for matching
ldy #0
ldx #0 ; Command buffer now contains our API call
phx ; We stash the current command number on the stack
WGAmpersand_matchLoop:
lda WGAmpersandCommandBuffer,y
beq WGAmpersand_matchFound ; Got one!
cmp WGAmpersandCommandTable,x
bne WGAmpersand_matchNext ; Not this one
iny
inx
bra WGAmpersand_matchLoop
WGAmpersand_matchNext:
pla ; Advance index to next commmand in table
inc
pha
asl
asl
asl
asl
tax
cpx #WGAmpersandCommandTableEnd-WGAmpersandCommandTable
beq WGAmpersand_matchFail ; Hit the end of the table
ldy #0
bra WGAmpersand_matchLoop
WGAmpersand_matchFound:
pla ; This is now the matching command number
inc
asl
asl
asl
asl
tay
lda WGAmpersandCommandTable-2,y ; Prepare an indirect JSR to our command
sta WGAmpersand_commandJSR+1 ; Self-modifying code!
lda WGAmpersandCommandTable-1,y
sta WGAmpersand_commandJSR+2
; Self-modifying code!
WGAmpersand_commandJSR:
jsr WGAmpersand_done ; Address here overwritten with command
bra WGAmpersand_done
WGAmpersand_matchFail:
pla ; We left command number on the stack while matching
ldx #ERR_UNDEFINEDFUNC
jsr ERROR
WGAmpersand_done:
RESTORE_ZPP
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersandIntArguments
; Buffers integer arguments for the current command in PARAMx
; TXTPTR: Start of argument list (after opening parenthesis)
; OUT PARAMx : The arguments
WGAmpersandIntArguments:
SAVE_AXY
ldy #0
phy ; Can't rely on Applesoft routines to be register-safe
lda #'('
jsr SYNCHR ; Expect opening parenthesis
WGAmpersandIntArguments_loop:
jsr GETBYT
txa
ply
sta PARAM0,y
phy
jsr CHRGOT
cmp #')' ; All done!
beq WGAmpersandIntArguments_cleanup
jsr CHKCOM ; Verify parameter separator
ply
iny
phy
cpy #4 ; Check for too many arguments
bne WGAmpersandIntArguments_loop
WGAmpersandIntArguments_fail:
ldx #ERR_TOOLONG
jsr ERROR
bra WGAmpersandIntArguments_done
WGAmpersandIntArguments_cleanup:
jsr CHRGET ; Consume closing parenthesis
WGAmpersandIntArguments_done:
ply
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersandStructArgument
; Buffers integer arguments for current command into a struct
; TXTPTR: Start of argument list (after opening parenthesis)
; OUT PARAM0/1 : Pointer to struct containing int values
WGAmpersandStructArgument:
SAVE_AXY
ldy #0
phy ; Can't rely on Applesoft routines to be register-safe
lda #'('
jsr SYNCHR ; Expect opening parenthesis
WGAmpersandStructArguments_loop:
jsr GETBYT
txa
ply
sta WGAmpersandCommandBuffer,y
phy
jsr CHRGOT
cmp #')' ; All done!
beq WGAmpersandStructArguments_cleanup
jsr CHKCOM ; Verify parameter separator
ply
iny
phy
cpy #WGAmpersandCommandBufferEnd-WGAmpersandCommandBuffer ; Check for too many arguments
bne WGAmpersandStructArguments_loop
WGAmpersandStructArguments_fail:
ldx #ERR_TOOLONG
jsr ERROR
bra WGAmpersandStructArguments_done
WGAmpersandStructArguments_cleanup:
jsr CHRGET ; Consume closing parenthesis
WGAmpersandStructArguments_done:
ply
lda #<WGAmpersandCommandBuffer
sta PARAM0
lda #>WGAmpersandCommandBuffer
sta PARAM1
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersandStrArgument
; Buffers a string argument for the current command in PARAM0/1
; TXTPTR: Start of argument list (after opening parenthesis)
; OUT PARAM0/1 : The argument
WGAmpersandStrArguments:
SAVE_AXY
ldy #0
phy ; Can't rely on Applesoft routines to be register-safe
lda #'('
jsr SYNCHR ; Expect opening parenthesis
WGAmpersandStrArguments_loop:
jsr CHRGOT
beq WGAmpersandStrArguments_tooShort
cmp #')'
beq WGAmpersandStrArguments_cleanup
ply
sta WGAmpersandCommandBuffer,y
iny
phy
cpy #WGAmpersandCommandBufferEnd-WGAmpersandCommandBuffer
beq WGAmpersandStrArguments_tooLong
jsr CHRGET
bra WGAmpersandStrArguments_loop
WGAmpersandStrArguments_tooLong:
ldx #ERR_TOOLONG
jsr ERROR
bra WGAmpersandStrArguments_done
WGAmpersandStrArguments_tooShort:
ldx #ERR_SYNTAX
jsr ERROR
bra WGAmpersandStrArguments_done
WGAmpersandStrArguments_cleanup:
jsr CHRGET ; Consume closing parenthesis
WGAmpersandStrArguments_done:
ply ; Null-terminate result
lda #0
sta WGAmpersandCommandBuffer,y
lda #<WGAmpersandCommandBuffer
sta PARAM0
lda #>WGAmpersandCommandBuffer
sta PARAM1
RESTORE_AXY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Ampersand API entry points
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersand_HOME
; Clears the screen
; &HOME
WGAmpersand_HOME:
jsr WGClearScreen
jsr WGBottomCursor
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersand_DESK
; Render the desktop
; &DESK
WGAmpersand_DESK:
jsr WGDesktop
jsr WGBottomCursor
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGAmpersand_WINDOW
; Create a view
; &WINDOW(id,style,x,y,width,height,canvas width,canvas height)
WGAmpersand_WINDOW:
jsr WGAmpersandStructArgument
jsr WGCreateView
jsr WGPaintView
jsr WGBottomCursor
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; WGBottomCursor
; Leave the cursor state in a place that Applesoft is happy with
;
WGBottomCursor:
SAVE_AY
lda #0
sta CH
sta OURCH
lda #23
sta CV
sta OURCV
lda TEXTLINES_H+23
sta BASH
lda TEXTLINES_L+23
sta BASL
RESTORE_AY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Applesoft API state
;
WGAmpersandCommandBuffer:
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.byte 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
WGAmpersandCommandBufferEnd:
.byte 0 ; Make sure this last byte is always kept as a terminator
; Jump table for ampersand commands.
; Each row is 16 bytes (14 for name, 2 for address)
WGAmpersandCommandTable:
.byte $97,0,0,0,0,0,0,0,0,0,0,0,0,0 ; HOME
.addr WGAmpersand_HOME
.byte "DESK",0,0,0,0,0,0,0,0,0,0
.addr WGAmpersand_DESK
.byte "WINDOW",0,0,0,0,0,0,0,0
.addr WGAmpersand_WINDOW
WGAmpersandCommandTableEnd:
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