Break up large source code files to help with dependency ordering

This commit is contained in:
Lucas Scharenbroich 2022-04-25 11:32:06 -05:00
parent 29d70dc567
commit d107365d79
9 changed files with 160 additions and 789 deletions

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@ -23,4 +23,7 @@ _GTEStatus MAC
<<<
_GTEReadControl MAC
UserTool $900+GTEToolNum
<<<
<<<
_GTESetScreenMode MAC
UserTool $A00+GTEToolNum
<<<

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@ -87,16 +87,17 @@ Overlay EXT
; Assumes the direct page is set and EngineMode and UserId has been initialized
_CoreStartUp
jsr IntStartUp ; Enable certain interrupts
jsr IntStartUp ; Enable certain interrupts
jsr InitMemory ; Allocate and initialize memory for the engine
jsr EngineReset ; All of the resources are allocated, put the engine in a known state
jsr InitMemory ; Allocate and initialize memory for the engine
; jsr EngineReset ; All of the resources are allocated, put the engine in a known state
; jsr InitGraphics ; Initialize all of the graphics-related data
; jsr InitSprites ; Initialize the sprite subsystem
; jsr InitTiles ; Initialize the tile subsystem
jsr InitTimers ; Initialize the timer subsystem
; jsr InitTimers ; Initialize the timer subsystem
rts
_CoreShutDown
jsr IntShutDown

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@ -11,12 +11,17 @@ InitGraphics
lda #0
jsr _SetPalette
jsr _InitBG0 ; Initialize the background layers
jsr _InitBG1
jsr _InitBG0 ; Initialize the background layer
lda EngineMode
bit #ENGINE_MODE_TWO_LAYER
beq :no_bg1
jsr _InitBG1
lda #0
jsr _ClearBG1Buffer
:no_bg1
rts
DefaultPalette dw $0000,$007F,$0090,$0FF0
@ -24,7 +29,6 @@ DefaultPalette dw $0000,$007F,$0090,$0FF0
dw $0fa9,$0ff0,$00e0,$04DF
dw $0d00,$078f,$0ccc,$0FFF
; Allow the user to dynamically select one of the pre-configured screen sizes, or pass
; in a specific width and height. The screen is automatically centered. If this is
; not desired, then SetScreenRect should be used directly
@ -224,9 +228,132 @@ _WaitForVBL
rep #$20
rts
; Set the physical location of the virtual screen on the physical screen. The
; screen size must by a multiple of 8
;
; A = XXYY where XX is the left edge [0, 159] and YY is the top edge [0, 199]
; X = width (in bytes)
; Y = height (in lines)
;
; This subroutine stores the screen positions in the direct page space and fills
; in the double-length ScreenAddrR table that holds the address of the right edge
; of the playfield. This table is used to set addresses in the code banks when the
; virtual origin is changed.
;
; We are not concerned about the raw performance of this function because it should
; usually only be executed once during app initialization. It doesn't get called
; with any significant frequency.
SetScreenRect sty ScreenHeight ; Save the screen height and width
stx ScreenWidth
tax ; Temp save of the accumulator
and #$00FF
sta ScreenY0
clc
adc ScreenHeight
sta ScreenY1
txa ; Restore the accumulator
xba
and #$00FF
sta ScreenX0
clc
adc ScreenWidth
sta ScreenX1
lda ScreenHeight ; Divide the height in scanlines by 8 to get the number tiles
lsr
lsr
lsr
sta ScreenTileHeight
lda ScreenWidth ; Divide width in bytes by 4 to get the number of tiles
lsr
lsr
sta ScreenTileWidth
lda ScreenY0 ; Calculate the address of the first byte
asl ; of the right side of the playfield
tax
lda ScreenAddr,x ; This is the address for the left edge of the physical screen
clc
adc ScreenX1
dec
pha ; Save for second loop
ldx #0
ldy ScreenHeight
jsr :loop
pla ; Reset the address and continue filling in the
ldy ScreenHeight ; second half of the table
:loop clc
sta RTable,x
adc #160
inx
inx
dey
bne :loop
; Calculate the screen locations for each tile corner
lda ScreenY0 ; Calculate the address of the first byte
asl ; of the right side of the playfield
tax
lda ScreenAddr,x ; This is the address for the left edge of the physical screen
clc
adc ScreenX0
ldx #0
ldy #0
:tsloop
stal TileStore+TS_SCREEN_ADDR,x
clc
adc #4 ; Go to the next tile
iny
cpy #41 ; If we've done 41 columns, move to the next line
bcc :nohop
ldy #0
clc
adc #{8*160}-{4*41}
:nohop
inx
inx
cpx #TILE_STORE_SIZE-2
bcc :tsloop
rts
; Clear the SHR screen and then infill the defined field
FillScreen lda #0
jsr _ClearToColor
ldy ScreenY0
:yloop
tya
asl a
tax
lda ScreenAddr,x
clc
adc ScreenX0
tax
phy
lda ScreenWidth
lsr
tay
lda #$FFFF
:xloop stal $E10000,x ; X is the absolute address
inx
inx
dey
bne :xloop
ply
iny
cpy ScreenY1
bcc :yloop
rts

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@ -121,6 +121,7 @@ InitMemory lda EngineMode
brl :bloop
:exit1
ldx #0
ldy #0
:bloop2

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@ -1,4 +1,4 @@
; Support routinges for the primary background
; Support routines for the primary background
_InitBG0
lda #DIRTY_BIT_BG0_X+DIRTY_BIT_BG0_Y
tsb DirtyBits

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@ -4,7 +4,6 @@ _InitBG1
jsr _ApplyBG1XPos
rts
; Copy a binary image data file into BG1. Assumes the file is the correct size (328 x 208)
;
; A=low word of picture address
@ -193,59 +192,6 @@ _ApplyBG1XPos
pld
rts
ANGLEBNK ext
ApplyBG1XPosAngle ENT
phb
phk
plb
jsr _ApplyBG1XPosAngle
plb
rtl
_ApplyBG1XPosAngle
; phy
; lda BG1StartX
; jsr Mod164
; sta BG1StartXMod164
; lda #162
; sec
; sbc StartXMod164
; bpl *+6
; clc
; adc #164
; clc
; adc BG1StartXMod164
; cmp #164
; bcc *+5
; sbc #164
; clc
; adc 1,s
; tay ; cache the value
; pla ; pop the value
phd ; save the direct page because we are going to switch to the
lda BlitterDP ; blitter direct page space and fill in the addresses
tcd
lda #^ANGLEBNK
sta $fe
sty $fc ; Store in the new direct page
ldy #162
tyx
:loop
lda [$fc],y
sta 00,x ; store the value
dey
dey
dex
dex
bpl :loop
pld
rts
_ClearBG1Buffer
phb
pha
@ -266,88 +212,6 @@ _ClearBG1Buffer
plb
rts
ApplyBG1YPosAngle ENT
phb
phk
plb
jsr _ApplyBG1YPosAngle
plb
rtl
_ApplyBG1YPosAngle
:virt_line equ tmp0
:lines_left equ tmp1
:draw_count equ tmp2
:ytbl_idx equ tmp3
:angle_tbl equ tmp4
sty :angle_tbl
lda BG1StartY
jsr Mod208
sta BG1StartYMod208
sta :ytbl_idx ; Start copying from the first entry in the table
lda StartYMod208 ; This is the base line of the virtual screen
sta :virt_line ; Keep track of it
lda ScreenHeight
sta :lines_left
:loop
lda :virt_line
asl
tax
ldal BTableLow,x ; Get the address of the first code field line
tay
sep #$20
ldal BTableHigh,x
pha ; push the bank on the stack
plb
rep #$20
lda :virt_line
and #$000F
eor #$FFFF
inc
clc
adc #16
min :lines_left
sta :draw_count ; Do this many lines
asl
tax
lda :ytbl_idx ; Read from this location (duplicate every 4 lines)
lsr
lsr
asl
clc
adc :angle_tbl
sec
sbc #ANGLEBNK
jsr CopyAngleYTableToBG1Addr ; or CopyBG1YTableToBG1Addr2
lda :virt_line ; advance to the virtual line after the segment we just
clc ; filled in
adc :draw_count
sta :virt_line
lda :ytbl_idx ; advance the index into the YTable
adc :draw_count
sta :ytbl_idx
lda :lines_left ; subtract the number of lines we just completed
sec
sbc :draw_count
sta :lines_left
jne :loop
phk
plb
rts
; Everytime either BG1 or BG0 Y-position changes, we have to update the Y-register
; value in all of the code fields (within the visible screen)
@ -494,97 +358,6 @@ CopyBG1YTableToBG1Addr
sta: BG1_ADDR+$0000,y
:none rts
; Unrolled copy routine to move y_angle entries into BG1_ADDR position with an additional
; shift. This has to be split into two
;
; A = index into the array (x2)
; Y = starting line * $1000
; X = number of lines (x2)
CopyAngleYTableToBG1Addr
phx
phb
phk ; restore access to this bank
plb
jsr SaveBG1AngleValues
plb
plx ; x is used directly in this routine
jsr ApplyBG1OffsetValues
rts
SaveBG1AngleValues
jmp (:tbl,x)
:tbl da :none
da :do01,:do02,:do03,:do04
da :do05,:do06,:do07,:do08
da :do09,:do10,:do11,:do12
da :do13,:do14,:do15,:do16
:do15 tax
bra :x15
:do14 tax
bra :x14
:do13 tax
bra :x13
:do12 tax
bra :x12
:do11 tax
bra :x11
:do10 tax
bra :x10
:do09 tax
bra :x09
:do08 tax
bra :x08
:do16 tax
ldal ANGLEBNK+06,x
sta BG1YCache+30
:x15 ldal ANGLEBNK+06,x
sta BG1YCache+28
:x14 ldal ANGLEBNK+06,x
sta BG1YCache+26
:x13 ldal ANGLEBNK+06,x
sta BG1YCache+24
:x12 ldal ANGLEBNK+04,x
sta BG1YCache+22
:x11 ldal ANGLEBNK+04,x
sta BG1YCache+20
:x10 ldal ANGLEBNK+04,x
sta BG1YCache+18
:x09 ldal ANGLEBNK+04,x
sta BG1YCache+16
:x08 ldal ANGLEBNK+02,x
sta BG1YCache+14
:x07 ldal ANGLEBNK+02,x
sta BG1YCache+12
:x06 ldal ANGLEBNK+02,x
sta BG1YCache+10
:x05 ldal ANGLEBNK+02,x
sta BG1YCache+08
:x04 ldal ANGLEBNK+00,x
sta BG1YCache+06
:x03 ldal ANGLEBNK+00,x
sta BG1YCache+04
:x02 ldal ANGLEBNK+00,x
sta BG1YCache+02
:x01 ldal ANGLEBNK+00,x
sta BG1YCache+00
:none rts
:do07 tax
bra :x07
:do06 tax
bra :x06
:do05 tax
bra :x05
:do04 tax
bra :x04
:do03 tax
bra :x03
:do02 tax
bra :x02
:do01 tax
bra :x01
; Unrolled copy routine to move BG1YTable entries into BG1_ADDR position with an additional
; shift. This has to be split into two
;
@ -738,7 +511,3 @@ ApplyBG1OffsetValues
:none rts
BG1YCache ds 32

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@ -59,7 +59,7 @@ _BltRange
; beq :primary
; lda BG1AltBank
; bra :alt
:primary lda BG1DataBank
:primary lda BG1DataBank ; This is $00 if the TWO_LAYER bit of EngineMode is not set
:alt
pha
plb

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@ -20,25 +20,25 @@
; Remember, because the data is pushed on to the stack, the last instruction, which is
; in the highest memory location, pushed data that apepars on the left edge of the screen.
;PER_TILE_SIZE equ 3
;]step equ 0
PER_TILE_SIZE equ 3
]step equ 0
; dw CODE_TOP ; There is a spot where we load Col2CodeOffet-2,x
;Col2CodeOffset lup 82
; dw CODE_TOP+{{81-]step}*PER_TILE_SIZE}
;]step equ ]step+1
; --^
; dw CODE_TOP+{81*PER_TILE_SIZE}
dw CODE_TOP ; There is a spot where we load Col2CodeOffet-2,x
Col2CodeOffset lup 82
dw CODE_TOP+{{81-]step}*PER_TILE_SIZE}
]step equ ]step+1
--^
dw CODE_TOP+{81*PER_TILE_SIZE}
; A parallel table to Col2CodeOffset that holds the offset to the exception handler address for each column
;SNIPPET_SIZE equ 32
;]step equ 0
; dw SNIPPET_BASE
;JTableOffset lup 82
; dw SNIPPET_BASE+{{81-]step}*SNIPPET_SIZE}
;]step equ ]step+1
; --^
; dw SNIPPET_BASE+{81*SNIPPET_SIZE}
SNIPPET_SIZE equ 32
]step equ 0
dw SNIPPET_BASE
JTableOffset lup 82
dw SNIPPET_BASE+{{81-]step}*SNIPPET_SIZE}
]step equ ]step+1
--^
dw SNIPPET_BASE+{81*SNIPPET_SIZE}
; Table of BRA instructions that are used to exit the code field. Separate tables for
; even and odd aligned cases.
@ -275,6 +275,7 @@ RTable ds 400
; Array of addresses for the banks that hold the blitter.
BlitBuff ENT
dw $5a5a
ds 4*13
; The blitter table (BTable) is a double-length table that holds the full 4-byte address of each

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@ -42,7 +42,7 @@ PagePatches da {long_0-base+2}
]index equ 0
lup 82 ; All the snippet addresses. The two JMP
da {snippets-base+{]index*32}+31} ; instructino are at the end of each of
da {snippets-base+{]index*32}+31} ; instructions are at the end of each of
da {snippets-base+{]index*32}+28} ; the 32-byte buffers
]index equ ]index+1
--^
@ -58,537 +58,6 @@ BankPatches da {long_0-base+3}
da {long_6-base+3}
BankPatchNum equ *-BankPatches
; Set the physical location of the virtual screen on the physical screen. The
; screen size must by a multiple of 8
;
; A = XXYY where XX is the left edge [0, 159] and YY is the top edge [0, 199]
; X = width (in bytes)
; Y = height (in lines)
;
; This subroutine stores the screen positions in the direct page space and fills
; in the double-length ScreenAddrR table that holds the address of the right edge
; of the playfield. This table is used to set addresses in the code banks when the
; virtual origin is changed.
;
; We are not concerned about the raw performance of this function because it should
; usually only be executed once during app initialization. It doesn't get called
; with any significant frequency.
SetScreenRect sty ScreenHeight ; Save the screen height and width
stx ScreenWidth
tax ; Temp save of the accumulator
and #$00FF
sta ScreenY0
clc
adc ScreenHeight
sta ScreenY1
txa ; Restore the accumulator
xba
and #$00FF
sta ScreenX0
clc
adc ScreenWidth
sta ScreenX1
lda ScreenHeight ; Divide the height in scanlines by 8 to get the number tiles
lsr
lsr
lsr
sta ScreenTileHeight
lda ScreenWidth ; Divide width in bytes by 4 to get the number of tiles
lsr
lsr
sta ScreenTileWidth
lda ScreenY0 ; Calculate the address of the first byte
asl ; of the right side of the playfield
tax
lda ScreenAddr,x ; This is the address for the left edge of the physical screen
clc
adc ScreenX1
dec
pha ; Save for second loop
ldx #0
ldy ScreenHeight
jsr :loop
pla ; Reset the address and continue filling in the
ldy ScreenHeight ; second half of the table
:loop clc
sta RTable,x
adc #160
inx
inx
dey
bne :loop
; Calculate the screen locations for each tile corner
lda ScreenY0 ; Calculate the address of the first byte
asl ; of the right side of the playfield
tax
lda ScreenAddr,x ; This is the address for the left edge of the physical screen
clc
adc ScreenX0
ldx #0
ldy #0
:tsloop
stal TileStore+TS_SCREEN_ADDR,x
clc
adc #4 ; Go to the next tile
iny
cpy #41 ; If we've done 41 columns, move to the next line
bcc :nohop
ldy #0
clc
adc #{8*160}-{4*41}
:nohop
inx
inx
cpx #TILE_STORE_SIZE-2
bcc :tsloop
rts
; Generalized routine that calculates the on-screen address of the tiles and takes the
; StartX and StartY values into consideration. This routine really exists to support
; the dirty tile rendering mode and the tiles *must* be aligned with the playfield.
; That is, StartX % 4 == 0 and StartY % 8 == 0. If these conditions are not met, then
; screen will not render correctly.
_RecalcTileScreenAddrs
NextColPtr equ tmp0
RowAddrPtr equ tmp1
OnScreenAddr equ tmp2
Counter equ tmp3
jsr _OriginToTileStore ; Get the (col,row) of the tile in the upper-left corner of the playfield
; Manually add the offsets to the NextCol and TileStoreYTable array address and put in a direct page
; location so we can free up the registers.
clc
txa
adc #NextCol
sta NextColPtr
tya
adc #TileStoreYTable
sta RowAddrPtr
; Calculate the on-screen address of the upper-left corner of the playfiled
lda ScreenY0 ; Calculate the address of the first byte
asl ; of the right side of the playfield
tax
lda ScreenAddr,x ; This is the address for the left edge of the physical screen
clc
adc ScreenX0
sta OnScreenAddr
; Now, loop through the tile store
lda #MAX_TILES
sta Counter
ldy #0
:tsloop
lda (NextColPtr),y ; Need to recalculate each time since the wrap-around could
clc ; happen anywhere
adc (RowAddrPtr) ;
tax ; NOTE: Try to rework to use new TileStore2DLookup array
lda OnScreenAddr
stal TileStore+TS_SCREEN_ADDR,x
clc
adc #4 ; Go to the next tile
iny
iny
cpy #2*41 ; If we've done 41 columns, move to the next line
bcc :nohop
inc RowAddrPtr ; Advance the row address (with wrap-around)
inc RowAddrPtr
ldy #0 ; Reset the column counter
clc
adc #{8*160}-{4*41}
:nohop
sta OnScreenAddr ; Save the updated on-screen address
dec Counter
bne :tsloop
rts
; Clear the SHR screen and then infill the defined field
FillScreen lda #0
jsr _ClearToColor
ldy ScreenY0
:yloop
tya
asl a
tax
lda ScreenAddr,x
clc
adc ScreenX0
tax
phy
lda ScreenWidth
lsr
tay
lda #$FFFF
:xloop stal $E10000,x ; X is the absolute address
inx
inx
dey
bne :xloop
ply
iny
cpy ScreenY1
bcc :yloop
rts
; Special subroutine to divide the accumulator by 164 and return remainder in the Accumulator
;
; 164 = $A4 = 1010_0100
Mod164 cmp #%1010010000000000
bcc *+5
sbc #%1010010000000000
cmp #%0101001000000000
bcc *+5
sbc #%0101001000000000
cmp #%0010100100000000
bcc *+5
sbc #%0010100100000000
cmp #%0001010010000000
bcc *+5
sbc #%0001010010000000
cmp #%0000101001000000
bcc *+5
sbc #%0000101001000000
cmp #%0000010100100000
bcc *+5
sbc #%0000010100100000
cmp #%0000001010010000
bcc *+5
sbc #%0000001010010000
cmp #%0000000101001000
bcc *+5
sbc #%0000000101001000
cmp #%0000000010100100
bcc *+5
sbc #%0000000010100100
rts
; Special subroutine to divide the accumulator by 208 and return remainder in the Accumulator
;
; 208 = $D0 = 1101_0000
;
; There are probably faster hacks to divide a 16-bit unsigned value by 208
; https://www.drdobbs.com/parallel/optimizing-integer-division-by-a-constan/184408499
; https://embeddedgurus.com/stack-overflow/2009/06/division-of-integers-by-constants/
Mod208 cmp #%1101000000000000
bcc *+5
sbc #%1101000000000000
cmp #%0110100000000000
bcc *+5
sbc #%0110100000000000
cmp #%0011010000000000
bcc *+5
sbc #%0011010000000000
cmp #%0001101000000000
bcc *+5
sbc #%0001101000000000
cmp #%0000110100000000
bcc *+5
sbc #%0000110100000000
cmp #%0000011010000000
bcc *+5
sbc #%0000011010000000
cmp #%0000001101000000
bcc *+5
sbc #%0000001101000000
cmp #%0000000110100000
bcc *+5
sbc #%0000000110100000
cmp #%0000000011010000
bcc *+5
sbc #%0000000011010000
rts
; Patch an 8-bit or 16-bit valueS into the bank. These are a set up unrolled loops to
; quickly patch in a constanct value, or a value from an array into a given set of
; templates.
;
; Because we have structured everything as parallel code blocks, most updates to the blitter
; reduce to storing a constant value and have an amortized cost of just a single store.
;
; The utility of these routines is that they also handle setting just a range of lines
; within a single bank.
;
; X = number of lines * 2, 0 to 32
; Y = starting line * $1000
; A = value
;
; Set M to 0 or 1
SetConst ; Need a blank line here, otherwise the :tbl local variable resolveds backwards
jmp (:tbl,x)
:tbl da :bottom-00,:bottom-03,:bottom-06,:bottom-09
da :bottom-12,:bottom-15,:bottom-18,:bottom-21
da :bottom-24,:bottom-27,:bottom-30,:bottom-33
da :bottom-36,:bottom-39,:bottom-42,:bottom-45
da :bottom-48
:top sta $F000,y
sta $E000,y
sta $D000,y
sta $C000,y
sta $B000,y
sta $A000,y
sta $9000,y
sta $8000,y
sta $7000,y
sta $6000,y
sta $5000,y
sta $4000,y
sta $3000,y
sta $2000,y
sta $1000,y
sta: $0000,y
:bottom rts
; SetDPAddrs
;
; A = absolute address (largest)
; Y = offset
;
; Initializes a bank of direct page offsets
SetDPAddrs
lda #$0800
sta $F000,y
lda #$0700
sta $E000,y
lda #$0600
sta $D000,y
lda #$0500
sta $C000,y
lda #$0400
sta $B000,y
lda #$0300
sta $A000,y
lda #$0200
sta $9000,y
lda #$0100
sta: $8000,y
lda #$0800
sta $7000,y
lda #$0700
sta $6000,y
lda #$0600
sta $5000,y
lda #$0500
sta $4000,y
lda #$0400
sta $3000,y
lda #$0300
sta $2000,y
lda #$0200
sta $1000,y
lda #$0100
sta: $0000,y
rts
; SetAbsAddrs
;
; A = absolute address (largest)
; Y = offset
; X = number of lines
;
; Stores a value and decrements by $1000 for each line
SetAbsAddrs sec
jmp (:tbl,x)
:tbl da :bottom-00,:bottom-03,:bottom-09,:bottom-15
da :bottom-21,:bottom-27,:bottom-33,:bottom-39
da :bottom-45,:bottom-51,:bottom-57,:bottom-63
da :bottom-69,:bottom-75,:bottom-81,:bottom-87
da :bottom-93
:top sta $F000,y
sbc #$1000
sta $E000,y
sbc #$1000
sta $D000,y
sbc #$1000
sta $C000,y
sbc #$1000
sta $B000,y
sbc #$1000
sta $A000,y
sbc #$1000
sta $9000,y
sbc #$1000
sta $8000,y
sbc #$1000
sta $7000,y
sbc #$1000
sta $6000,y
sbc #$1000
sta $5000,y
sbc #$1000
sta $4000,y
sbc #$1000
sta $3000,y
sbc #$1000
sta $2000,y
sbc #$1000
sta $1000,y
sbc #$1000
sta: $0000,y
:bottom rts
; Fill up a full bank with blitter templates. Currently we can fit 16 lines per bank, so need
; a total of 13 banks to hold the 208 lines for full-screen support
;
; A = high word of bank table
; Y = index * 4 of the bank to initialize
BuildBank
:bankArray equ tmp0
:target equ tmp2
:nextBank equ tmp4
stx :bankArray
sta :bankArray+2
stz :target
iny
iny
lda [:bankArray],y
sta :target+2
iny ; move to the next item
iny
iny ; middle byte
cpy #4*13 ; if greater than the array length, wrap back to zero
bcc :ok
ldy #1
:ok lda [:bankArray],y ; Get the middle and high bytes of the address
sta :nextBank
:next
jsr :BuildLine2
lda :target
clc
adc #$1000
sta :target
bcc :next
phb
pei :target+1
plb
plb
; Change the patched value to one of DP_ENTRY, TWO_LYR_ENTRY or ONE_LYR_ENTRY based on the capabilities
; that the engine needs.
lda #$F000+{DP_ENTRY} ; Set the address from each line to the next
ldy #CODE_EXIT+1
ldx #15*2
jsr SetAbsAddrs
ldy #DP_ADDR
jsr SetDPAddrs
ldy #$F000+CODE_EXIT ; Patch the last line with a JML to go to the next bank
lda #{$005C+{DP_ENTRY}*256}
sta [:target],y
ldy #$F000+CODE_EXIT+2
lda :nextBank
sta [:target],y
ldy #$8000+CODE_EXIT ; Patch one line per bank to enable interrupts
lda #{$004C+{ENABLE_INT}*256}
sta [:target],y
plb
rts
; This is the relocation subroutine, it is responsible for copying the template to a
; memory location and patching up the necessary instructions.
;
; X = low word of address (must be a multiple of $1000)
; A = high word of address (bank)
:BuildLine
stx :target
sta :target+2
:BuildLine2
lda #CODE_LEN ; round up to an even number of bytes
inc
and #$FFFE
beq :nocopy
dec
dec
tay
:loop lda base,y
sta [:target],y
dey
dey
bpl :loop
:nocopy lda #0 ; copy is complete, now patch up the addresses
sep #$20
ldx #0
lda :target+2 ; patch in the bank for the absolute long addressing mode
:dobank ldy BankPatches,x
sta [:target],y
inx
inx
cpx #BankPatchNum
bcc :dobank
ldx #0
:dopage ldy PagePatches,x ; patch the page addresses by adding the page offset to each
lda [:target],y
clc
adc :target+1
sta [:target],y
inx
inx
cpx #PagePatchNum
bcc :dopage
:out
rep #$20
rts
; Start of the template code. This code is replicated 16 times per bank and spans
; 13 banks for a total of 208 lines, which is what is required to render 26 tiles
; to cover the full screen vertical scrolling.