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Slower but more universal pitch table generator
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@ADM228
ADM228 committed Jan 20, 2024
1 parent e08869d commit 04dcb89
Showing 1 changed file with 115 additions and 47 deletions.
162 changes: 115 additions & 47 deletions source/sound/SNESFM.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -323,6 +323,8 @@ InternalDefines:
INSDATA_TMP_PTR_1_L = $6E
INSDATA_TMP_PTR_1_H = $6F

L001_PrevPitch_Lo = $EE

warnings enable W1008
;

Expand Down Expand Up @@ -386,6 +388,9 @@ Init: ;init routine by KungFuFurby
if !SNESFM_CFG_PITCHTABLE_GEN >= 1
MOV A, #$7D
MOV Y, #$21
MOVW L001_PrevPitch_Lo, YA
MOV A, #$39
MOV Y, #$0F
CALL GeneratePitchTable_Start
endif

Expand Down Expand Up @@ -1836,8 +1841,7 @@ SendCPUMsg:
WaitCPUMsg:
-:
MOV A, $F4
CMP A, MESSAGE_CNT_TH1
BNE -
CBNE MESSAGE_CNT_TH1, -
INC MESSAGE_CNT_TH1
MOV A, $F5
AND A, #$F0
Expand Down Expand Up @@ -2745,79 +2749,143 @@ GeneratePitchTable:
; Inputs:
; YA = base pitch value of C7
.Defines:
GenPitch_CounterA = $EA
GenPitch_NewPitch_Lo = $EC
GenPitch_NewPitch_Hi = $ED
GenPitch_PrevPitch_Lo = $EE
GenPitch_PrevPitch_Hi = $EF
!GenPitch_Ratio_Lo = $E8
!GenPitch_Ratio_Hi = $E9

!L001_CounterA = $EA

!L001_NewPitch_Lo = $EB
!L001_NewPitch_Md = $EC
!L001_NewPitch_Hi = $ED

!L001_PrevPitch_Lo = $EE
!L001_PrevPitch_Hi = $EF

!GenPitch_RatioMult = 196 ; 196/185 ≈ 2^(1/12) - the ratio for 1 semitone
!GenPitch_RatioDiv = 185 ;__

!GenPitch_Ratio12Lo = #$39
!GenPitch_Ratio12Hi = #$0F
.Start:

MOVW !GenPitch_Ratio_Lo, YA
MOV !L001_CounterA, X
MOVW YA, !L001_PrevPitch_Lo
MOV PitchTableLo+(7*12), A
MOV PitchTableHi+(7*12), Y
MOV GenPitch_PrevPitch_Lo, A
MOV GenPitch_PrevPitch_Hi, Y

MOV X, #$00
; .OldSemitoneUpLoop:
; MOV !L001_CounterA, X

; MOV Y, !L001_PrevPitch_Lo ;
; MOV A, #!GenPitch_RatioMult ;
; MUL YA ; Multiply low byte
; MOV !L001_NewPitch_Lo, A ;
; MOV !L001_NewPitch_Hi, Y ;__

; MOV !L001_PrevPitch_Lo, #$00 ;
; MOV Y, !L001_PrevPitch_Hi ;
; MOV A, #!GenPitch_RatioMult ; Multiply high byte
; MUL YA ;__
; ADDW YA, !L001_NewPitch_Hi ; The next byte is 0, so it adds only the high byte as the mid byte

; MOV X, #!GenPitch_RatioDiv ; YA very conveniently stores the high and mid bytes
; DIV YA, X ; Divide mid and high bytes
; MOV !L001_NewPitch_Hi, A ;__

; MOV A, !L001_NewPitch_Lo ; Y very conveniently stores the remainder as the high byte
; MOV X, #!GenPitch_RatioDiv ; Divide low byte with remainder as high byte
; DIV YA, X ;__
; CMP Y, #!GenPitch_RatioDiv/2 ; Round the number
; ADC A, #$00 ;__

; MOV X, !L001_CounterA ;
; MOV PitchTableLo+(7*12)+1+X, A ; Store low byte
; MOV !L001_PrevPitch_Lo, A ;__
; MOV A, !L001_NewPitch_Hi ;
; MOV PitchTableHi+(7*12)+1+X, A ; Store high byte
; MOV !L001_PrevPitch_Hi, A ;__

; INC X
; CMP X, #11
; BNE GeneratePitchTable_OldSemitoneUpLoop

; old: 123 cycles
; new: 150-158 cycles

.SemitoneUpLoop:
MOV GenPitch_CounterA, X

MOV Y, GenPitch_PrevPitch_Lo ;
MOV A, #!GenPitch_RatioMult ;
MUL YA ; Multiply low byte
MOV GenPitch_NewPitch_Lo, A ;
MOV GenPitch_NewPitch_Hi, Y ;__

MOV GenPitch_PrevPitch_Lo, #$00 ;
MOV Y, GenPitch_PrevPitch_Hi ;
MOV A, #!GenPitch_RatioMult ; Multiply high byte
MUL YA ;__
ADDW YA, GenPitch_NewPitch_Hi ; The next byte is 0, so it adds only the high byte as the mid byte

MOV X, #!GenPitch_RatioDiv ; YA very conveniently stores the high and mid bytes
DIV YA, X ; Divide mid and high bytes
MOV GenPitch_NewPitch_Hi, A ;__

MOV A, GenPitch_NewPitch_Lo ; Y very conveniently stores the remainder as the high byte
MOV X, #!GenPitch_RatioDiv ; Divide low byte with remainder as high byte
DIV YA, X ;__
CMP Y, #!GenPitch_RatioDiv/2 ; Round the number
ADC A, #$00 ;__

MOV X, GenPitch_CounterA ;
MOV PitchTableLo+(7*12)+1+X, A ; Store low byte
MOV GenPitch_PrevPitch_Lo, A ;__
MOV A, GenPitch_NewPitch_Hi ;
MOV PitchTableHi+(7*12)+1+X, A ; Store high byte
MOV GenPitch_PrevPitch_Hi, A ;__
MOV Y, !L001_PrevPitch_Hi ;
MOV A, !GenPitch_Ratio_Hi ; Multiply Hi * Hi
MUL YA ;
MOVW !L001_NewPitch_Md, YA ;__

MOV Y, !L001_PrevPitch_Lo ;
MOV A, !GenPitch_Ratio_Lo ; Multiply Lo * Lo
MUL YA ;__
ASL A ;- Equal to CMP #$80 but 1 less byte
MOV A, Y ;
ADC A, #$00 ; Round the lowest byte out
BCC + ;
INCW !L001_NewPitch_Md ;
+ MOV !L001_NewPitch_Lo, A ;__

MOV Y, !L001_PrevPitch_Lo ;
MOV A, !GenPitch_Ratio_Hi ;
MUL YA ; Multiply Lo * Hi
ADDW YA, !L001_NewPitch_Lo ;
ADC !L001_NewPitch_Hi, #$00 ;
MOVW !L001_NewPitch_Lo, YA ;__

MOV Y, !L001_PrevPitch_Hi ;
MOV A, !GenPitch_Ratio_Lo ;
MUL YA ;__ Multiply Hi * Lo
ADDW YA, !L001_NewPitch_Lo ; Add final Mid&Lo bytes
MOV !L001_NewPitch_Md, Y ;__
ASL A ;- Equal to CMP #$80 but 1 byte less
BCC + ; Round low byte
INCW !L001_NewPitch_Md ;__
+

ASL !L001_NewPitch_Md ;__ Round mid byte (CMP #$80 but 1 byte and 1 cycle less)
ADC !L001_PrevPitch_Lo, !L001_NewPitch_Md
ADC !L001_PrevPitch_Hi, !L001_NewPitch_Hi
MOV A, !L001_PrevPitch_Lo ; Store the low pitch byte
MOV PitchTableLo+(7*12)+1+X, A ;__
MOV A, !L001_PrevPitch_Hi ; Store the high pitch byte
MOV PitchTableHi+(7*12)+1+X, A ;__
INC X
CMP X, #11
CMP X, !L001_CounterA
BNE GeneratePitchTable_SemitoneUpLoop

.BitShiftStart:
MOV GenPitch_CounterA, #12
MOV !L001_CounterA, #12

.BitShiftBigLoop:
CLRC
MOV A, #6*12
ADC A, GenPitch_CounterA
ADC A, !L001_CounterA
MOV X, A
MOV A, PitchTableHi+12-1+X
MOV GenPitch_NewPitch_Hi, A
MOV !L001_NewPitch_Hi, A
MOV A, PitchTableLo+12-1+X

..BitShiftLoop:
LSR GenPitch_NewPitch_Hi ;
LSR !L001_NewPitch_Hi ;
ROR A ;
ADC A, #$00 ;
ADC GenPitch_NewPitch_Hi, #$00 ;__
ADC !L001_NewPitch_Hi, #$00 ;__
MOV Y, A

MOV PitchTableLo-1+X, A
MOV A, GenPitch_NewPitch_Hi
MOV A, !L001_NewPitch_Hi
MOV PitchTableHi-1+X, A

MOV A, X
Expand All @@ -2829,7 +2897,7 @@ GeneratePitchTable:
MOV A, Y
JMP GeneratePitchTable_BitShiftBigLoop_BitShiftLoop
+:
DBNZ GenPitch_CounterA, GeneratePitchTable_BitShiftBigLoop
DBNZ !L001_CounterA, GeneratePitchTable_BitShiftBigLoop
.OverflowCorrection:
MOV X, #7*12+11
Expand Down

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