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optimize amplitude code

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Peter Ferrie 2019-06-01 00:29:56 -04:00 committed by Vince Weaver
parent 6f56cfc254
commit d0d0e06f1c
1 changed files with 6 additions and 8 deletions
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14
pt3_player/pt3_lib.s
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@ -707,17 +707,15 @@ calc_amplitude:
; adjust amplitude sliding
lda sample_b0 ; if ((b0 & 0x80)!=0) {
and #$80
beq done_amp_sliding ; so if top bit not set, skip
bit sample_b0 ; if ((b0 & 0x80)!=0) {
bpl done_amp_sliding ; so if top bit not set, skip
;================================
; if top bits 0b11 then slide up
; if top buts 0b10 then slide down
lda sample_b0 ; if ((b0&0x40)!=0) {
and #$40
beq amp_slide_down
; if ((b0 & 0x40)!=0) {
bvc amp_slide_down
amp_slide_up:
; if (a->amplitude_sliding < 15) {
@ -730,7 +728,7 @@ amp_slide_up:
asu_signed:
bpl done_amp_sliding ; skip if A>=15
inc note_a+NOTE_AMPLITUDE_SLIDING,X ; a->amplitude_sliding++;
jmp done_amp_sliding
bne done_amp_sliding
amp_slide_down:
; if (a->amplitude_sliding > -15) {
@ -759,7 +757,7 @@ done_amp_sliding:
check_amp_lo:
bpl check_amp_hi
lda #0
jmp write_clamp_amplitude
beq write_clamp_amplitude
check_amp_hi:
cmp #16