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Add triangle wave back in with counters

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This commit is contained in:
Lucas Scharenbroich 2023-06-16 08:18:02 -05:00
parent 99184396fc
commit 24cd424d7c
1 changed files with 74 additions and 12 deletions
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86
demos/smb/apu.s
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@ -326,9 +326,9 @@ backup_interrupt_ptr ds 4
; APU internals
;-----------------------------------------------------------------------------------------
mx %11
clock_length mac
clock_length_counter mac
lda ]1+{APU_PULSE1_REG1-APU_PULSE1}
bit #PULSE_HALT_FLAG
bit ]2
bne no_count
lda ]1+{APU_PULSE1_LENGTH_COUNTER-APU_PULSE1}
beq no_count
@ -336,6 +336,25 @@ clock_length mac
sta ]1+{APU_PULSE1_LENGTH_COUNTER-APU_PULSE1}
no_count <<<
clock_linear_counter mac
lda ]1+{APU_TRIANGLE_START_FLAG-APU_TRIANGLE}
beq do_clock
lda ]1+{APU_TRIANGLE_REG1-APU_TRIANGLE}
and #$7F
sta ]1+{APU_TRIANGLE_LINEAR_COUNTER-APU_TRIANGLE}
bra check_reset
do_clock lda ]1+{APU_TRIANGLE_LINEAR_COUNTER-APU_TRIANGLE}
beq check_reset
dec
sta ]1+{APU_TRIANGLE_LINEAR_COUNTER-APU_TRIANGLE}
check_reset
lda ]1+{APU_TRIANGLE_REG1-APU_TRIANGLE}
bmi no_reset
stz ]1+{APU_TRIANGLE_START_FLAG-APU_TRIANGLE}
no_reset <<<
clock_sweep mac
lda ]1+{APU_PULSE1_SWEEP_DIVIDER-APU_PULSE1}
dec
@ -451,6 +470,7 @@ envelope_out <<<
apu_frame_steps equ 5
PULSE_HALT_FLAG equ $20
PULSE_CONST_VOL_FLAG equ $10
TRIANGLE_HALT_FLAG equ $80
interrupt_handler = *
@ -486,8 +506,9 @@ interrupt_handler = *
:half_frame
; clock the length counters
clock_length APU_PULSE1
clock_length APU_PULSE2
clock_length_counter APU_PULSE1;#PULSE_HALT_FLAG
clock_length_counter APU_PULSE2;#PULSE_HALT_FLAG
clock_length_counter APU_TRIANGLE;#TRIANGLE_HALT_FLAG
; clock the sweep units
clock_sweep APU_PULSE1;0
@ -497,6 +518,8 @@ interrupt_handler = *
:quarter_frame
; clock the envelopes and triangle linear counter
clock_linear_counter APU_TRIANGLE
clock_envelope APU_PULSE1
clock_envelope APU_PULSE2
@ -585,6 +608,16 @@ interrupt_handler = *
; Now the triangle wave. This wave needs linear counter support to be silenced
; brl :not_timer
lda #$40+triangle_oscillator
sta sound_address
lda APU_TRIANGLE_LENGTH_COUNTER ; If the length counter is zero, no output
beq :set_volume_triangle
lda APU_TRIANGLE_LENGTH_COUNTER
beq :set_volume_triangle
lda #12 ; Triangle is a bit softer than pulse channels
:set_volume_triangle
jsr set_pulse_volume
rep #$30
lda APU_TRIANGLE_REG3
jsr get_pulse_freq ; return freq in 16-bic accumulator
@ -781,6 +814,11 @@ APU_TRIANGLE_REG2 ds 1 ; EPPP NSSS - Sweep unit: enabled, period, negative, s
APU_TRIANGLE_REG3 ds 1 ; LLLL LLLL - Timer Low
APU_TRIANGLE_REG4 ds 1 ; llll lHHH - Length counter load, timer high (also resets duty and starts envelope)
APU_TRIANGLE_LENGTH_COUNTER dfb 0
APU_TRIANGLE_CURRENT_PERIOD dw 0
APU_TRIANGLE_START_FLAG dfb 0
APU_TRIANGLE_LINEAR_COUNTER dfb 0
APU_STATUS ds 1
mx %11
@ -898,11 +936,38 @@ APU_TRIANGLE_REG2_WRITE ENT
rtl
APU_TRIANGLE_REG3_WRITE ENT
stal APU_TRIANGLE_CURRENT_PERIOD
stal APU_TRIANGLE_REG3
rtl
APU_TRIANGLE_REG4_WRITE ENT
php
phx
pha
stal APU_TRIANGLE_REG4
and #$07
stal APU_TRIANGLE_CURRENT_PERIOD+1
ldal APU_STATUS
bit #$04
beq :no_reload
ldal APU_TRIANGLE_REG4
and #$F8
lsr
lsr
lsr
tax
ldal LengthTable,x
stal APU_TRIANGLE_LENGTH_COUNTER ; Immediately start the counter
lda #1
stal APU_TRIANGLE_START_FLAG
:no_reload
pla
plx
plp
rtl
@ -926,14 +991,11 @@ APU_STATUS_WRITE ENT
stz APU_PULSE2_LENGTH_COUNTER
:pulse2_on
; Triangle is OSC 4
; bit #$03
; beq :triangle_off
; _SetDOCReg #$40+triangle_oscillator;#128
; bra :triangle_end
;:triangle_off
; _SetDOCReg #$40+triangle_oscillator;#0
;:triangle_end
; Triangle
bit #$04
bne :triangle_on
stz APU_TRIANGLE_LENGTH_COUNTER
:triangle_on
pla
rtl