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optimize envelope code

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This commit is contained in:
Peter Ferrie 2019-06-01 00:36:03 -04:00 committed by Vince Weaver
parent d0d0e06f1c
commit 3c4d32eaba
1 changed files with 18 additions and 16 deletions
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34
pt3_player/pt3_lib.s
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@ -810,15 +810,23 @@ check_envelope_enable:
envelope_slide:
lda sample_b0
lsr
tay
; Envelope slide
; If b1 top bits are 10 or 11
lda #$80
bit sample_b1
beq else_noise_slide ; if ((b1 & 0x80) != 0) {
lda #$20
bit sample_b0
php
bit sample_b1
bpl else_noise_slide ; if ((b1 & 0x80) != 0) {
plp
php
;;bug? always falls through
beq envelope_slide_down ; if ((b0 & 0x20) != 0) {
; FIXME: this can be optimized
@ -826,17 +834,16 @@ envelope_slide:
envelope_slide_down:
; j = ((b0>>1)|0xF0) + a->envelope_sliding
lda sample_b0
lsr
tya
ora #$f0
clc
adc note_a+NOTE_ENVELOPE_SLIDING,X
sta e_slide_amount ; j
;;+jmp envelope_slide_done?
envelope_slide_up:
; j = ((b0>>1)&0xF) + a->envelope_sliding;
lda sample_b0
lsr
tya
and #$0f
clc
adc note_a+NOTE_ENVELOPE_SLIDING,X
@ -844,12 +851,10 @@ envelope_slide_up:
envelope_slide_done:
lda #$20
bit sample_b1
plp
beq last_envelope ; if (( b1 & 0x20) != 0) {
; a->envelope_sliding = j;
lda e_slide_amount
sta note_a+NOTE_ENVELOPE_SLIDING,X
last_envelope:
@ -868,18 +873,15 @@ else_noise_slide:
; else {
; pt3->noise_add = (b0>>1) + a->noise_sliding;
lda sample_b0
lsr
tya
clc
adc note_a+NOTE_NOISE_SLIDING,X
sta pt3_noise_add
lda #$20
bit sample_b1
plp
beq noise_slide_done ; if ((b1 & 0x20) != 0) {
; noise_sliding = pt3_noise_add
lda pt3_noise_add
sta note_a+NOTE_NOISE_SLIDING,X
noise_slide_done: