First implementation of BG0/BG1 mixed exception handling
This commit is contained in:
Lucas Scharenbroich
parent
6fc772ce78
commit
bdf885dafd
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@ -16,8 +16,13 @@ MoveRight
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sec
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sbc 1,s
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bpl *+5
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lda #163
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lda #0
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jsr SetBG0XPos
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lda StartX
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lsr
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jsr SetBG1XPos
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jsr DoFrame
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pla
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rts
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@ -25,10 +30,12 @@ MoveRight
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MoveDown
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clc
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adc StartY ; Increment the virtual X-position
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cmp #207
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bcc *+5
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lda #0
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jsr SetBG0YPos
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lda StartY
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lsr
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jsr SetBG1YPos
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jsr DoFrame
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rts
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@ -38,8 +45,13 @@ MoveUp
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sec
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sbc 1,s
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bpl *+5
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lda #207
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lda #0
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jsr SetBG0YPos
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lda StartY
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lsr
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jsr SetBG1YPos
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jsr DoFrame
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pla
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rts
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@ -87,3 +99,8 @@ FPSStr str 'FPS'
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107
src/App.Main.s
107
src/App.Main.s
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@ -406,6 +406,8 @@ CopyPicToField
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:line_cnt equ tmp2
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:dstptr equ tmp3
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:col_cnt equ tmp5
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:mask equ tmp6
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:data equ tmp7
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sta :srcptr
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stx :srcptr+2
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@ -429,26 +431,63 @@ CopyPicToField
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:cloop
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phy
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lda [:srcptr],y ; load the picture data
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beq :transparent ; a value of $0000 is transparent
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jsr :toMask ; Infer a mask value for this. If it's $0000, then
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bne :mixed ; the data is solid, otherwise mixed
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; This is a solid word
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lda [:srcptr],y
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ldy Col2CodeOffset,x ; Get the offset to the code from the line start
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cmp #0 ; Empty values are transparent
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beq :transparent
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pha
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pha ; Save the data
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lda #$00F4 ; PEA instruction
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sta [:dstptr],y
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iny
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pla
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sta [:dstptr],y
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sta [:dstptr],y ; PEA operand
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bra :next
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:transparent
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ldy Col2CodeOffset,x ; Get the offset to the code from the line start
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lda #$B1 ; LDA (dp),y
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sta [:dstptr],y
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iny
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lda 1,s ; load the saved Y-index
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ora #$4800 ; put a PHA after the offset
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sta [:dstptr],y
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bra :next
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:mixed
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sta :mask ; Save the mask
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lda [:srcptr],y ; Refetch the screen data
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sta :data
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ldy Col2CodeOffset,x ; Get the offset into the code field
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lda #$4C ; JMP exception
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sta [:dstptr],y
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iny
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lda JTableOffset,x ; Get the address offset and add to the base address
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clc
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adc :dstptr
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sta [:dstptr],y
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ldy JTableOffset,x ; This points to the code fragment
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lda 1,s ; load the offset
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xba
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ora #$00B1
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sta [:dstptr],y ; write the LDA (--),y instruction
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iny
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iny
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iny ; advance to the AND #imm operand
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lda :mask
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sta [:dstptr],y
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iny
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iny
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iny ; advance to the ORA #imm operand
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lda :data
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sta [:dstptr],y
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:next
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ply
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@ -469,8 +508,35 @@ CopyPicToField
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inc :line_cnt
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lda :line_cnt
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cmp #200
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bcc :rloop
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bcs :exit
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brl :rloop
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:exit
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rts
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:toMask bit #$F000
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beq *+7
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and #$0FFF
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bra *+5
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ora #$F000
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bit #$0F00
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beq *+7
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and #$F0FF
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bra *+5
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ora #$0F00
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bit #$00F0
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beq *+7
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and #$FF0F
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bra *+5
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ora #$00F0
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bit #$000F
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beq *+7
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and #$FFF0
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bra *+5
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ora #$000F
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rts
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; Copy a binary image data file into BG1. Assumes the file is the correct size.
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@ -872,6 +938,35 @@ qtRec adrl $0000
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@ -8,6 +8,10 @@ SetBG1XPos
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sta BG1StartX
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rts
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SetBG1YPos
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sta BG1StartY
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rts
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; Everytime either BG1 or BG0 X-position changes, we have to update the direct page values. We
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; *could* do this by adjusting the since address offset, but we have to change up to 200 values
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; when the vertical position changes, and only 41 when the horizontal value changes. Plus
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@ -247,5 +251,6 @@ CopyBG1YTableToBG1Addr
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@ -28,6 +28,9 @@ StartXMod164 equ 36
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BG1StartX equ 38 ; Logical offset of the second background
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BG1StartXMod164 equ 40
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BG1StartY equ 42
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BG1StartYMod208 equ 44
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bstk equ 208 ; 16-byte stack to push bank addresses
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tmp8 equ 224
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@ -66,4 +69,5 @@ DIRTY_BIT_BG1_Y equ $0008
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@ -22,6 +22,15 @@ Col2CodeOffset lup 82
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--^
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dw CODE_TOP
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; A parallel table to Col2CodeOffset that hold the offset to the exception handler address for each column
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SNIPPET_SIZE equ 32
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]step equ 0
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JTableOffset lup 82
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dw SNIPPET_BASE+{]step*SNIPPET_SIZE}
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]step equ ]step+1
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--^
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dw SNIPPET_BASE
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; Table of BRA instructions that are used to exit the code field. Separate tables for
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; even and odd aligned cases.
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;
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@ -16,11 +16,12 @@ ODD_ENTRY equ odd_entry-base+1
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CODE_TOP equ loop-base
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CODE_LEN equ top-base
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CODE_EXIT equ even_exit-base
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OPCODE_SAVE equ odd_exit-base+1 ; spot to save the code field opcode when patching exit BRA
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OPCODE_HIGH_SAVE equ odd_high_byte-base+1 ; save the third byte
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OPCODE_SAVE equ odd_save-base ; spot to save the code field opcode when patching exit BRA
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OPCODE_HIGH_SAVE equ odd_save-base+2 ; save the third byte
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FULL_RETURN equ full_return-base ; offset that returns from the blitter
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ENABLE_INT equ enable_int-base ; offset that re-enable interrupts and continues
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LINES_PER_BANK equ 16
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SNIPPET_BASE equ snippets-base
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; Locations that need the page offset added
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PagePatches da {long_0-base+2}
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@ -456,10 +457,10 @@ right_odd bit #$000B ; Check the bottom nibble
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long_1 stal *+4-base ; Everything else is a two-byte LDA opcode + PHA
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dfb $00,$00
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bra r_is_pea+1
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bra r_jmp_rtn
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r_is_pea xba ; fast code for PEA
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sep #$20
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r_jmp_rtn sep #$20 ; shared return code path by all methods
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pha
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rep #$20
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odd_entry jmp $0100 ; unconditionally jump into the "next" instruction in the
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@ -475,7 +476,7 @@ odd_entry jmp $0100 ; unconditionally jump in
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r_is_jmp sep #$41 ; Set the C and V flags which tells a snippet to push only the low byte
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long_2 ldal entry_jmp+1-base
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long_3 stal *+5-base
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dfb $4C,$00,$00 ; Jump back to address in entry_jmp (this takes 16 cycles, is there a better way?)
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jmp $0000 ; Jumps into the exception code, which return to r_jmp_rtn
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; The next labels are special, in that they are entry points into special subroutines. They are special
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; because they are within the first 256 bytes of each code field, which allows them to be selectable
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@ -517,16 +518,13 @@ loop lup 82 ; +6 Set up 82 PEA inst
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loop_back jmp loop-base ; +252 Ensure execution continues to loop around
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loop_exit_3 jmp even_exit-base ; +255
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odd_exit lda #0000 ; This operand field is *always* used to hold the original 2 bytes of the code field
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; that are replaced by the needed BRA instruction to exit the code field. When the
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; left edge is odd-aligned, we are able to immediately load the value and perform
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; similar logic to the right_odd code path above
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long_5
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odd_exit ldal l_is_jmp+1-base
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bit #$000B
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bne :chk_jmp
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sep #$20
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odd_high_byte lda #00 ; patch with high byte code operand
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long_6 ldal l_is_jmp+3-base ; get the high byte of the PEA operand
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; Fall-through when we have to push a byte on the left edge. Must be 8-bit on entry. Optimize
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; for the PEA $0000 case -- only 19 cycles to handle the edge, so pretty good
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@ -540,20 +538,18 @@ even_exit jmp $1000 ; Jump to the next line.
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:chk_jmp
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bit #$0040
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bne :l_is_jmp
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bne l_is_jmp
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long_4 stal *+4-base
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dfb $00,$00
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xba
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l_jmp_rtn xba
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sep #$20
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pha
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rep #$20
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bra even_exit
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:l_is_jmp sec ; Set the C flag (V is always cleared at this point) which tells a snippet to push only the high byte
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long_5 ldal entry_jmp+1-base
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long_6 stal *+5-base
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dfb $4C,$00,$00 ; Jump back to address in entry_jmp (this takes 13 cycles, is there a better way?)
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l_is_jmp sec ; Set the C flag (V is always cleared at this point) which tells a snippet to push only the high byte
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odd_save dfb $00,$00,$00 ; The odd exit 3-byte sequence is always stashed here
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; Special epilogue: skip a number of bytes and jump back into the code field. This is useful for
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; large, floating panels in the attract mode of a game, or to overlay solid
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@ -604,18 +600,24 @@ epilogue_1 tsc
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; jmp exit_rtn ; 3
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; r_edge jmp entry_rtn ; 3
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; snippets ds 32*82
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ds \,$00 ; pad to the next page boundary
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]index equ 0
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snippets lup 82
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ds 2 ; space for a 2-byte sequence; LDA (00),y LDA 00,x LDA 0,s
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and #$0000 ; the mask operand will be set when the tile is drawn
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ora #$0000 ; the data operand will be set when the tile is drawn
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pha
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bcs *+5
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brl loop+3+{3*]index} ; use relative branch for convenience
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bvs *+6 ; overflow set means this is the right edge (entry)
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clc ; carry is set only for edge operations; force clear
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brl l_jmp_rtn
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rep #$41 ; clear V and C
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brl r_jmp_rtn ; 25 bytes
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ds 7 ; padding
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]index equ ]index+1
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--^
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top
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