Initial addition of BG1 support
This commit is contained in:
Lucas Scharenbroich
parent
63bfe5e8e7
commit
abfcde54c2
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@ -49,8 +49,11 @@ MemInit PushLong #0 ; space for result
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plx ; base address of the new handle
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pla ; high address 00XX of the new handle (bank)
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_Deref
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stx ZeroPage
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sta ZeroPage+2
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stx BlitterDP
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; Allocate a bank of memory for BG1
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jsr AllocOneBank2
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sta BG1DataBank
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; Allocate the 13 banks of memory we need and store in double-length array
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]step equ 0
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@ -101,7 +104,6 @@ MemInit PushLong #0 ; space for result
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Buff00 ds 4
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Buff01 ds 4
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ZeroPage ds 4
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; Bank allocator (for one full, fixed bank of memory. Can be immediately deferenced)
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@ -189,6 +191,11 @@ ShutDown rts
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115
src/App.Main.s
115
src/App.Main.s
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@ -42,7 +42,7 @@ SHR_PALETTES equ $E19E00
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tiledata ext
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; Feature flags
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NO_INTERRUPTS equ 1 ; turn off for crossrunner debugging
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NO_INTERRUPTS equ 0 ; turn off for crossrunner debugging
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; Typical init
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@ -100,6 +100,8 @@ NO_INTERRUPTS equ 1 ; turn off for crossrunner
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lda #0 ; Set the virtual X-position
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jsr SetBG0XPos
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jsr _InitBG1 ; Initialize the second background
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; Load a picture and copy it into Bank $E1. Then turn on the screen.
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jsr AllocOneBank ; Alloc 64KB for Load/Unpack
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@ -176,7 +178,14 @@ EvtLoop
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jsr Demo
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brl EvtLoop
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:12 brl EvtLoop
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:12 cmp #'c'
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bne :13
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ldx #$00E1
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lda #$2000
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jsr CopyPicToField
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brl EvtLoop
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:13 brl EvtLoop
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; Exit code
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Exit
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@ -329,22 +338,99 @@ DoFrame
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rts
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; Load a simple picture format onto the SHR screen
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DoLoadPic
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lda BankLoad
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ldx #ImageName ; Load+Unpack Boot Picture
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jsr LoadPicture ; X=Name, A=Bank to use for loading
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lda BankLoad ; get address of loaded/uncompressed picture
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lda BankLoad ; Copy it into the code field
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clc
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adc #$0080 ; skip header?
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sta :copySHR+2 ; and store that over the 'ldal' address below
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ldx #$7FFE ; copy all image data
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:copySHR ldal $000000,x ; load from BankLoad we allocated
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stal SHR_SCREEN,x ; store to SHR screen
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adc #$0080
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xba
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pha
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and #$00FF
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tax
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pla
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and #$FF00
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jsr CopyPicToField
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rts
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; Copy a loaded SHR picture into the code field
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;
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; A=low word of picture address
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; X=high workd of pixture address
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;
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; Picture must be within one bank
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CopyPicToField
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:srcptr equ tmp0
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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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sta :srcptr
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stx :srcptr+2
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stz :line_cnt
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:rloop
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lda :line_cnt ; get the pointer to the code field line
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asl
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tax
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lda BTableLow,x
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sta :dstptr
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lda BTableHigh,x
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sta :dstptr+2
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ldx #162 ; move backwards in the code field
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ldy #0 ; move forward in the image data
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lda #80 ; keep a running column count
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sta :col_cnt
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:cloop
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phy
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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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lda #$00F4 ; PEA instruction
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sta [:dstptr],y
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iny
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pla
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sta [:dstptr],y
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bra :next
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:transparent
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lda #$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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:next
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ply
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dex
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dex
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bpl :copySHR
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iny
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iny
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dec :col_cnt
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bne :cloop
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lda :srcptr
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clc
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adc #160
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sta :srcptr
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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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rts
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****************************************
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@ -667,3 +753,12 @@ qtRec adrl $0000
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put blitter/Template.s
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put blitter/Tiles.s
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put blitter/Vert.s
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put blitter/BG1.s
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@ -66,6 +66,7 @@ Render
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jsr _ApplyBG0XPos ; Patch the PEA instructions with exit BRA opcode
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jsr _ApplyBG0YPos ; Set stack addresses for the virtual lines to the physical screen
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jsr _ApplyBG1XPos ; Adjust the direct page pointers to the BG1 bank
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ldx #0 ; Blit the full virtual buffer to the screen
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ldy ScreenHeight
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@ -86,3 +87,4 @@ Render
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@ -0,0 +1,204 @@
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; Initialization and setup routines for the second background
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_InitBG1
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jsr _ApplyBG1XPos
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jsr _ApplyBG1YPos
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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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; these are all direct page values
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;
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; Note: This routine can be optimized as an unrolled loop of PEI instructions
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_ApplyBG1XPos
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lda #162
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sec
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sbc StartXMod164
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bpl *+6
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clc
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adc #164
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tay
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phd ; save the direct page because we are going to switch to the
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lda BlitterDP ; blitter direct page space and fill in the addresses
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tcd
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tya
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ldx #162
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:loop
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sta 00,x ; store the value
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dec
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dec
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bpl *+6
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clc
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adc #164
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dex
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dex
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bpl :loop
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pld
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rts
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; Everytime either BG1 or BG0 Y-position changes, we have to update the Y-register
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; value in all of the code fields (within the visible screen)
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_ApplyBG1YPos
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:virt_line equ tmp0
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:lines_left equ tmp1
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:draw_count equ tmp2
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:ytbl_idx equ tmp3
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stz :rtbl_idx ; Start copying from the first entry in the table
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lda StartY ; This is the base line of the virtual screen
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sta :virt_line ; Keep track of it
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lda ScreenHeight
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sta :lines_left
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:loop
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lda :virt_line
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asl
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tax
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ldal BTableLow,x ; Get the address of the first code field line
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tay
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sep #$20
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ldal BTableHigh,x
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pha
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plb ; This is the bank that will receive the updates
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rep #$20
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lda :virt_line
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and #$000F
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eor #$FFFF
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inc
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clc
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adc #16
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min :lines_left
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sta :draw_count ; Do this many lines
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asl
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tax
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lda :ytbl_idx ; Read from this location in the BG1YTable
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asl
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jsr CopyBG1YTableToBG1Addr
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lda :virt_line ; advance to the virtual line after the segment we just
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clc ; filled in
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adc :draw_count
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sta :virt_line
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lda :ytbl_idx ; advance the index into the YTable
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adc :draw_count
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sta :ytbl_idx
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lda :lines_left ; subtract the number of lines we just completed
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sec
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sbc :draw_count
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sta :lines_left
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jne :loop
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phk
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plb
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rts
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; Unrolled copy routine to move BG1YTable entries into BG1_ADDR position.
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;
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; A = intect into the BG1YTable array (x2)
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; Y = starting line * $1000
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; X = number of lines (x2)
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CopyBG1YTableToBG1Addr
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jmp (:tbl,x)
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:tbl da :none
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da :do01,:do02,:do03,:do04
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da :do05,:do06,:do07,:do08
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da :do09,:do10,:do11,:do12
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da :do13,:do14,:do15,:do16
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:do15 tax
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bra :x15
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:do14 tax
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bra :x14
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:do13 tax
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bra :x13
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:do12 tax
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bra :x12
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:do11 tax
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bra :x11
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:do10 tax
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bra :x10
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:do09 tax
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bra :x09
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:do08 tax
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bra :x08
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:do07 tax
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bra :x07
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:do06 tax
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bra :x06
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:do05 tax
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bra :x05
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:do04 tax
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bra :x04
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:do03 tax
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bra :x03
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:do02 tax
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bra :x02
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:do01 tax
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bra :x01
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:do16 tax
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ldal BG1YTable+30,x
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sta BG1_ADDR+$F000,y
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:x15 ldal BG1YTable+28,x
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sta BG1_ADDR+$E000,y
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:x14 ldal BG1YTable+26,x
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sta BG1_ADDR+$D000,y
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:x13 ldal BG1YTable+24,x
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sta BG1_ADDR+$C000,y
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:x12 ldal BG1YTable+22,x
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sta BG1_ADDR+$B000,y
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:x11 ldal BG1YTable+20,x
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sta BG1_ADDR+$A000,y
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:x10 ldal BG1YTable+18,x
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sta BG1_ADDR+$9000,y
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:x09 ldal BG1YTable+16,x
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sta BG1_ADDR+$8000,y
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:x08 ldal BG1YTable+14,x
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sta BG1_ADDR+$7000,y
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:x07 ldal BG1YTable+12,x
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sta BG1_ADDR+$6000,y
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:x06 ldal BG1YTable+10,x
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sta BG1_ADDR+$5000,y
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:x05 ldal BG1YTable+08,x
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sta: BG1_ADDR+$4000,y
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:x04 ldal BG1YTable+06,x
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sta BG1_ADDR+$3000,y
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:x03 ldal BG1YTable+04,x
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sta BG1_ADDR+$2000,y
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:x02 ldal BG1YTable+02,x
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sta BG1_ADDR+$1000,y
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:x01 ldal BG1YTable+00,x
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sta: BG1_ADDR+$0000,y
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:none rts
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@ -15,12 +15,13 @@ EngineMode equ 20 ; Defined the mode/capabilities that are ena
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DirtyBits equ 22 ; Identify values that have changed between frames
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BG1DataBank equ 24 ; Data bank that holds BG1 layer data
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BlitterDP equ 25 ; Direct page address the holder blitter data
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BlitterDP equ 26 ; Direct page address the holder blitter data
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OldStartX equ 26
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OldStartY equ 28
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OldStartX equ 28
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OldStartY equ 30
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LastPatchOffset equ 30 ; Offset into code field that was patched with BRA instructions
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LastPatchOffset equ 32 ; Offset into code field that was patched with BRA instructions
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StartXMod164 equ 34
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bstk equ 208 ; 16-byte stack to push bank addresses
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@ -56,3 +57,5 @@ DIRTY_BIT_BG1_Y equ $0008
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@ -192,7 +192,7 @@ _ApplyBG0XPos
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lda StartX ; This is the starting byte offset (0 - 163)
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jsr Mod164 ;
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pha ; Save for a bit
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sta StartXMod164
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; Now, the left edge of the screen is pushed last, so we need to exit one instruction *after*
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; the location (163 - StartX % 164)
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@ -218,7 +218,7 @@ _ApplyBG0XPos
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lda #163
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sec
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sbc 1,s
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sbc StartXMod164
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tay
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; Right now we have the offset of the last visible byte. Add one to get the offset
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@ -243,7 +243,7 @@ _ApplyBG0XPos
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tax
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lda CodeFieldEvenBRA,x
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sta :exit_bra
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lda Col2CodeOffset,X
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lda Col2CodeOffset,x
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sta :exit_offset
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sta LastPatchOffset ; Cache as a flag for later
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bra :do_entry
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@ -294,7 +294,6 @@ _ApplyBG0XPos
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lda #$00AF ; set the entry_jmp opcode to LDAL
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sta :opcode
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:prep_complete
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pla ; Pop off the saved value
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; Main loop that
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;
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@ -742,3 +741,7 @@ SetCodeEntryOpcode
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sta CODE_ENTRY_OPCODE+$1000,y
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sta: CODE_ENTRY_OPCODE+$0000,y
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:bottom rts
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@ -215,3 +215,19 @@ BlitBuff ds 4*13
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; that everything can use the same indexing offsets
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BTableHigh ds 208*2*2
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BTableLow ds 208*2*2
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; A double-length table of addresses for the BG1 bank. The BG1 buffer is 208 rows of 256 bytes each and
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; the first row starts 256 bytes in to give enough room for scroll adjustments
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]step equ 256
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BG1YTable lup 208
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dw ]step
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]step = ]step+256
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--^
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]step equ 256
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lup 208
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dw ]step
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]step = ]step+256
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--^
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@ -695,13 +695,13 @@ BuildBank
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plb
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plb
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lda #$F000+{ONE_LYR_ENTRY} ; Set the address from each line to the next
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lda #$F000+{TWO_LYR_ENTRY} ; Set the address from each line to the next
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ldy #CODE_EXIT+1
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ldx #15*2
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jsr SetAbsAddrs
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ldy #$F000+CODE_EXIT ; Patch the last line with a JML to go to the next bank
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lda #{$005C+{ONE_LYR_ENTRY}*256}
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lda #{$005C+{TWO_LYR_ENTRY}*256}
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sta [target],y
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ldy #$F000+CODE_EXIT+2
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lda nextBank
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@ -938,3 +938,7 @@ epilogue_1 tsc
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; snippets ds 32*82
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top
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@ -188,11 +188,3 @@ CopyRTableToStkAddr
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sta: STK_ADDR+$0000,y
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:none rts
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