dos33fsprogs/vaporlock/rasterbars/pt3_lib_make_frame.s

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;========================================================================
; EVERYTHING IS CYCLE COUNTED
;========================================================================
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; Note, can save cycles if we don't have early-exit (check)
; also if we don't have to convert from 1.77
; the logic here:
;
; if (current_line==0) && (subframe==0) {
; set_pattern();
;; }
; if (subframe==0) {
; decode_line();
; }
; else {
; }
; if (pattern_done) {
;
; }
; subframe++;
; if (subframe==speed) {
; subframe=0;
; current_line++;
; if (current_line==64) {
; pattern++;
; current_line=0;
; }
; }
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;=====================================
;=====================================
;=====================================
; pt3 make frame
;=====================================
;=====================================
;=====================================
; update pattern or line if necessary
; then calculate the values for the next frame
; 8+373=381
; Paths
;
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; A (current_line)
;
; B (current subframe)
;
; C (pattern_done)
;
; D (always)
;
; F
;
; C
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;=============================
; State A
;=============================
pt3_make_frame:
; see if we need a new pattern
; we do if line==0 and subframe==0
; allow fallthrough where possible
current_line_smc:
lda #$d1 ; 2
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beq check_subframe ; 3
; -1
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;=============================
; State B
;=============================
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;
pattern_good:
; see if we need a new line
current_subframe_smc:
lda #$d1 ; 2
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bne line_good ; 3
; -1
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;=============================
; State C
;=============================
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;
pt3_new_line:
; decode a new line
jsr pt3_decode_line ; 6+?
; check if pattern done early
pt3_pattern_done_smc:
lda #$d1 ; 2
bne line_good ; 2/3
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;=============================
; State D
;=============================
;==========================
; pattern done early!
early_end:
; A is pattern_done which is zero at this point
inc current_pattern_smc+1 ; increment pattern ; 6
sta current_line_smc+1 ; 4
sta current_subframe_smc+1 ; 4
; always goes to set_pattern here?
jmp set_pattern ; 3
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;=============================
; State E
;=============================
check_subframe:
lda current_subframe_smc+1 ; 4
bne pattern_good ; 2/3
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;=============================
; State F
;=============================
set_pattern:
; load a new pattern in
jsr pt3_set_pattern ;6+?
jmp pt3_new_line ; 3
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;=============================
; State D
;=============================
;
line_good:
; Increment everything
inc current_subframe_smc+1 ; subframe++ ; 6
lda current_subframe_smc+1 ; 4
; if we hit pt3_speed, move to next
pt3_speed_smc:
eor #$d1 ; 2
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bne do_frame ; 3
; -1
;=============================
; State G
;=============================
;
next_line:
sta current_subframe_smc+1 ; reset subframe to 0 ; 4
inc current_line_smc+1 ; and increment line ; 6
lda current_line_smc+1 ; 4
eor #64 ; always end at 64. ; 2
bne do_frame ; is this always needed? ; 2/3
next_pattern:
sta current_line_smc+1 ; reset line to 0 ; 4
inc current_pattern_smc+1 ; increment pattern ; 6
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;==============================================
; falls through to do_frame