dos33fsprogs/xmas_2019/pt3_lib_write_frame.s

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2019-12-20 21:47:35 +00:00
; ZZ points to offset from pointer
;D0 F1 ;0 $9000,$9100,$9200 = A Low (reg0)
;D1 F2 ;1 $9300,$9400,$9500 = A high (reg1) [top], B high (reg3) [bottom]
;D2 F3 ;2 $9600,$9700,$9800 = B Low (reg2)
;D3 F4 ;3 $9900,$9A00,$9B00 = C Low (reg4)
;D4 F5 ;4 $9C00,$9D00,$9E00 = Envelope Shape (r13) [top], C high (reg5) [bot]
;D5 F6 ;5 $9F00,$A000,$A100 = Noise (r6), bit7 = don't change envelope
;D6 F7 ;6 $A200,$A300,$A400 = Enable (r7)
;D7 F8 ;7 $A500,$A600,$A700 = A amp (r8), bit 5 of r8,r9,r10
;D8 F9 ;8 $A800,$A900,$AA00 = C amp (r10) [top], B amp (r9) [bottom]
;D9 FA ;9 $AB00,$AC00,$AD00 = ENV low (r11)
;DA FB ;a $AE00,$AF00,$B000 = ENV high (r12)
pt3_write_frame:
ldy FRAME_OFFSET ; 3
;=====================
; Register 0: A fine
lda A_FINE_TONE
r0_wrsmc:
sta $D000,Y
;==========================
; Register 1/3: A/B coarse
lda A_COARSE_TONE
asl
asl
asl
asl
ora B_COARSE_TONE
r1_wrsmc:
sta $D100,Y
;====================
; Register 2: B fine
lda B_FINE_TONE
r2_wrsmc:
sta $D200,Y
;====================
; Register 3: B coarse already done
;=============================
; Register 4: C fine
lda C_FINE_TONE
r4_wrsmc:
sta $D300,Y
;=======================================
; Register 5: Envelope Shape [top] / C coarse [bottom]
lda C_COARSE_TONE
and #$f
sta C_COARSE_TEMP
lda ENVELOPE_SHAPE
cmp #$ff
beq no_envelope
yes_envelope:
lda ENVELOPE_SHAPE
asl
asl
asl
asl
ora C_COARSE_TEMP
sta C_COARSE_TEMP
lda #0
jmp done_envelope
no_envelope:
lda #$80
done_envelope:
sta ENV_SHAPE_TEMP
lda C_COARSE_TEMP
r13_wrsmc:
sta $D400,Y
;=====================
; Register 6: Noise
lda NOISE
and #$1f
ora ENV_SHAPE_TEMP
r6_wrsmc:
sta $D500,Y
;=====================
; Register 7: Enable
lda ENABLE
r7_wrsmc:
sta $D600,Y
;=====================
; Register 8: a-amp
lda A_VOLUME
and #$1f
sta A_VOL_TEMP
lda B_VOLUME
and #$10
asl
ora A_VOL_TEMP
sta A_VOL_TEMP
lda C_VOLUME
and #$10
asl
asl
ora A_VOL_TEMP
r8_wrsmc:
sta $D700,Y
;============================
; Register 9/10: b-amp (bottom) , c-amp (top)
lda B_VOLUME
and #$f
sta A_VOL_TEMP
lda C_VOLUME
asl
asl
asl
asl
ora A_VOL_TEMP
r9_wrsmc:
sta $D800,Y
;=====================
; Register 10: c-amp already handled
;=====================
; Register 11: E fine
lda ENVELOPE_FINE
r11_wrsmc:
sta $D900,Y
;=======================
; Register 12: E coarse
lda ENVELOPE_COARSE
r12_wrsmc:
sta $DA00,Y
;=============================
; Register 13: already handled
rts ; 6