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113 lines
2.0 KiB
ArmAsm
113 lines
2.0 KiB
ArmAsm
.include "equates.s"
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.include "macros.s"
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.org $0000
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FIRST_CHAR = 32
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; renderString (Far entry point)
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;
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; Draws a Pascal string
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;
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; PARAML0 = Pointer to string
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; X = Font index
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; Y = VRAM position of lower right corner of string at which to draw
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;
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; Trashes SCRATCHL,PARAML1,X, Y, A
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;
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renderString:
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NATIVE
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SAVE_DBR
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sty SCRATCHL ; Cache VRAM position
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txa ; Cache font character table
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asl
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tay
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lda fontJumpTable,y
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sta renderCharBounce+1
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lda fontCharWidthTable,y
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sta PARAML1
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plb ; Temporarily revert to caller's DBR to access their pointer
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BITS8
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lda (PARAML0)
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tax
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BITS16
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phb
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renderStringLoop:
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; Fetch and render next character in string
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txy
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lda #0
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plb ; Temporarily revert to caller's DBR to access their pointer
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BITS8A
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lda (PARAML0),y
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BITS16
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phb
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ldy SCRATCHL
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jsr renderChar
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dex
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beq renderStringDone
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; Calculate VRAM pointer for position of next character
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lda SCRATCHL
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sec
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sbc PARAML1
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sta SCRATCHL
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bra renderStringLoop
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renderStringDone:
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RESTORE_DBR
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rtl
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; renderChar
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;
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; Draws a single character
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;
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; A = ASCII code to draw
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; Y = VRAM position of lower right corner at which to draw
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;
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renderChar:
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SAVE_AXY
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sec ; Bounce off glyph-rendering jump table
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sbc #FIRST_CHAR
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asl
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tax
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FASTGRAPHICS
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renderCharBounce: ; Self modifying code. Don't panic
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jmp (font16characterJumpTable,x)
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renderCharJumpReturn: ; Compiled glyphs jump back here. Can't rts because stack is turboborked
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SLOWGRAPHICS
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RESTORE_AXY
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rts
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fontJumpTable:
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.addr font8characterJumpTable
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.addr font16characterJumpTable
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fontCharWidthTable: ; In bytes
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.word 4
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.word 8
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.include "font8x8.s"
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.include "font16x16.s"
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; Suppress some linker warnings - Must be the last thing in the file
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; This is because Quinn doesn't really know how to use ca65 properly
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.SEGMENT "ZPSAVE"
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.SEGMENT "EXEHDR"
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.SEGMENT "STARTUP"
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.SEGMENT "INIT"
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.SEGMENT "LOWCODE"
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