mirror of
https://github.com/a2-4am/4cade.git
synced 2024-06-27 03:29:30 +00:00
some comments
This commit is contained in:
4am
parent
b8f6fe13e4
commit
569269ccb5
|
|
@ -68,6 +68,8 @@
|
|||
;
|
||||
|
||||
!ifndef USES_CLEAR {
|
||||
; if an effect doesn't use any clear stages, you can reduce code size
|
||||
; by setting USES_CLEAR=0 before including this file
|
||||
USES_CLEAR = 1
|
||||
}
|
||||
|
||||
|
|
@ -82,7 +84,17 @@ hgrlo = $300 ; [$C0 bytes] HGR base addresses
|
|||
BoxesX = $200 ; [$30 bytes] starting row for each box
|
||||
BoxesY = $230 ; [$30 bytes] starting byte offset for each box
|
||||
|
||||
; high bytes of drawing routines for each stage (actual routine will be page-aligned)
|
||||
; High bytes of drawing routines for each stage (actual routines will be page-aligned).
|
||||
; To minimize code size, we build drawing routines in this order:
|
||||
; - copy01 (STAGE1 template)
|
||||
; - copy00 (STAGE0 template)
|
||||
; - copy0F..copy09 (OUTER_STAGE template)
|
||||
; - copy08..copy02 (MIDDLE_STAGE template)
|
||||
; - change some opcodes to turn the 'copy' routines into 'clear' routines
|
||||
; - clear0F..clear08 (OUTER_STAGE)
|
||||
; - clear07..clear02 (MIDDLE_STAGE)
|
||||
; - clear01 (STAGE1)
|
||||
; - clear00 (STAGE0)
|
||||
clear00 = $64
|
||||
clear01 = $65
|
||||
clear02 = $66
|
||||
|
|
@ -117,7 +129,9 @@ copy00 = $82
|
|||
copy01 = $83
|
||||
|
||||
; tokens for code generation
|
||||
k_rts = 0
|
||||
; used as indexes into |codegen_pieces| and |codegen_piece_lengths|,
|
||||
; so keep all three in sync
|
||||
k_rts = 0 ; must be 0
|
||||
k_inx_and_recalc = 1
|
||||
k_recalc = 2
|
||||
k_recalc_and_iny = 3
|
||||
|
|
@ -180,7 +194,9 @@ k_right_mask = 17
|
|||
bne -
|
||||
pla
|
||||
|
||||
jsr GenerateStages
|
||||
; drawing routines for each stage are constructed dynamically
|
||||
; and stored at copy00..copy0F and clear00..clear0F
|
||||
jsr BuildDrawingRoutines
|
||||
|
||||
; set up zero page for drawing phase
|
||||
; A=0 here
|
||||
|
|
@ -194,7 +210,6 @@ k_right_mask = 17
|
|||
; X=0 here
|
||||
+BUILD_HGR_LOOKUP_TABLES_X_IS_ALREADY_0 hgrlo, hgrhi
|
||||
|
||||
; any was initialized by the BoxStages copy loop
|
||||
MainLoop ldx #48
|
||||
BoxLoop stx box
|
||||
ldy BoxStages-1, x ; for each box, get its current stage
|
||||
|
|
@ -205,7 +220,7 @@ BoxLoop stx box
|
|||
lda BoxesX-1, x
|
||||
ldy BoxesY-1, x ; Y = starting byte offset for this box
|
||||
tax ; X = starting HGR row for this box
|
||||
inc any
|
||||
inc any ; was initialized by the BoxStages copy loop
|
||||
clc
|
||||
j jsr $FD00 ; [SMC] call drawing routine for this stage
|
||||
ldx box
|
||||
|
|
@ -217,10 +232,18 @@ NextBox dex
|
|||
bit $C000
|
||||
bpl MainLoop
|
||||
+
|
||||
; execution falls through here
|
||||
|
||||
; These are all the pieces of code we need to construct the drawing routines.
|
||||
; There are 32 drawing routines (16 if USES_CLEAR=0), which we construct from
|
||||
; four templates (below). Templates use tokens to refer to these code pieces.
|
||||
; Note that several pieces overlap in order to minimize code size.
|
||||
; Everything from CODEGEN_COPY_START and onward is copied to zero page for
|
||||
; the code generation phase on program startup.
|
||||
CODEGEN_COPY_START
|
||||
!pseudopc 0 {
|
||||
RTS0 ; 1 byte
|
||||
rts
|
||||
rts ; also terminates MainLoop
|
||||
RTS0_E
|
||||
INX_AND_RECALC ; 16 bytes
|
||||
inx
|
||||
|
|
@ -302,7 +325,7 @@ RIGHT_MASK ; 1 byte
|
|||
!byte $FD
|
||||
RIGHT_MASK_E
|
||||
|
||||
codegen_piece_lengths
|
||||
codegen_piece_lengths ; length of each of the pieces
|
||||
!byte RTS0_E-RTS0
|
||||
!byte INX_AND_RECALC_E-INX_AND_RECALC
|
||||
!byte RECALC_E-RECALC
|
||||
|
|
@ -322,7 +345,7 @@ codegen_piece_lengths
|
|||
!byte LEFT_MASK_E-LEFT_MASK
|
||||
!byte RIGHT_MASK_E-RIGHT_MASK
|
||||
|
||||
codegen_pieces
|
||||
codegen_pieces ; address of each of the pieces (on zero page, so 1 byte)
|
||||
!byte <RTS0
|
||||
!byte <INX_AND_RECALC
|
||||
!byte <RECALC
|
||||
|
|
@ -342,6 +365,8 @@ codegen_pieces
|
|||
!byte <LEFT_MASK
|
||||
!byte <RIGHT_MASK
|
||||
|
||||
; Template for 'stage 0' routine (copy00), which copies the innermost
|
||||
; part of the box (labeled '0' in diagram above).
|
||||
STAGE0
|
||||
!byte k_stage_init
|
||||
!byte k_recalc
|
||||
|
|
@ -349,7 +374,10 @@ STAGE0
|
|||
!byte k_maskcopy_pre, k_left_mask, k_maskcopy_post
|
||||
!byte k_inx_and_recalc
|
||||
!byte k_maskcopy_pre, k_left_mask, k_maskcopy_post
|
||||
!byte k_rts
|
||||
!byte k_rts ; also serves as an end-of-template marker
|
||||
|
||||
; Template for 'stage 1' routine (copy01), which copies the pixels
|
||||
; around the innermost box (labeled '1' in diagram above).
|
||||
STAGE1
|
||||
!byte k_stage_init
|
||||
!byte k_recalc
|
||||
|
|
@ -361,7 +389,9 @@ STAGE1
|
|||
!byte k_copy
|
||||
!byte k_inx_and_recalc
|
||||
!byte k_copy
|
||||
!byte k_rts
|
||||
!byte k_rts ; also serves as an end-of-template marker
|
||||
|
||||
; Template for stages 2-8 (copy02..copy08)
|
||||
MIDDLE_STAGE
|
||||
!byte k_stage_init
|
||||
!byte k_recalc_and_iny
|
||||
|
|
@ -375,7 +405,9 @@ MIDDLE_STAGE
|
|||
!byte k_dey2
|
||||
!byte k_inx_and_recalc
|
||||
!byte k_middle_branches
|
||||
!byte k_rts
|
||||
!byte k_rts ; also serves as an end-of-template marker
|
||||
|
||||
; Template for stages 9-15 (copy09..copy0F)
|
||||
OUTER_STAGE
|
||||
!byte k_stage_init
|
||||
!byte k_recalc
|
||||
|
|
@ -394,7 +426,7 @@ OUTER_STAGE
|
|||
!byte k_dey2
|
||||
!byte k_inx_and_recalc
|
||||
!byte k_outer_branches
|
||||
!byte k_rts
|
||||
!byte k_rts ; also serves as an end-of-template marker
|
||||
|
||||
EdgeRightMasks
|
||||
!byte %10000001
|
||||
|
|
@ -455,7 +487,7 @@ piece_src=*+1
|
|||
lda $FD, x ; SMC
|
||||
!byte $99,$00 ; STA $4400, Y
|
||||
codegen_dst
|
||||
!byte copy01
|
||||
!byte copy01 ; SMC
|
||||
iny
|
||||
inx
|
||||
piece_length=*+1
|
||||
|
|
@ -468,7 +500,7 @@ piece_length=*+1
|
|||
rts
|
||||
}
|
||||
|
||||
GenerateStages
|
||||
BuildDrawingRoutines
|
||||
; copy codegen data to zero page
|
||||
; X=0 here
|
||||
- lda CODEGEN_COPY_START, x
|
||||
|
|
@ -477,7 +509,7 @@ GenerateStages
|
|||
bne -
|
||||
|
||||
; generate drawing routines for copy01, then copy00
|
||||
jsr GenerateStage1And0
|
||||
jsr BuildStage1And0
|
||||
; A=0 here
|
||||
sta <FIRST_ROW
|
||||
|
||||
|
|
@ -499,7 +531,7 @@ GenerateStages
|
|||
dec <ROW_COUNT
|
||||
dec <ROW_COUNT
|
||||
dec <codegen_stage
|
||||
bmi GenerateStage1And0
|
||||
bmi BuildStage1And0
|
||||
lda <codegen_stage
|
||||
eor #13
|
||||
bne +
|
||||
|
|
@ -521,8 +553,8 @@ GenerateStages
|
|||
bmi ---
|
||||
bpl -- ; always branches
|
||||
|
||||
; generate drawing routines for clear01, then clear00, then exit
|
||||
GenerateStage1And0
|
||||
; generate drawing routines for copy01, copy00 (or clear01, clear00)
|
||||
BuildStage1And0
|
||||
lda #%10111110
|
||||
sta <LEFT_MASK
|
||||
lda #<STAGE1
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user