; DISCLAIMER ; ; Copyright (C) 1997 by Adrian Philip Whichello. All rights reserved. ; ; I, Adrian Philip Whichello, MAKE NO WARRANTY ON THIS SOFTWARE, EITHER EXPRESS ; OR IMPLIED, WITH RESPECT TO QUALITY, ACCURACY, MERCHANTABILITY, OR FITNESS FOR ; A PARTICULAR PURPOSE. ; ; IN NO EVENT WILL I BE HELD RESPONSIBLE FOR DIRECT, INDIRECT, SPECIAL, ; INCIDENTAL, OR CONSEQUENTIAL DAMAGES RESULTING FROM ANY DEFECT OF THE ; SOFTWARE. ; ; I RELEASE THIS PROGRAM AS FREEWARE. YOU MAY COPY, GIVE AWAY AND USE THIS ; PROGRAM, PROVIDED THIS NOTICE REMAINS ATTACHED AT ALL TIMES. ; return .equ 0 real .equ return+2 imag .equ real+2 N .equ imag+2 sign .equ N+2 scalfac .equ sign+2 i .equ scalfac+2 j .equ i+1 costab .equ j+1 mplier .equ costab+2 micand .equ mplier+2 result .equ micand+2 icos .equ result+2 isin .equ icos+1 tmp_re .equ isin+1 tmp_im .equ tmp_re+1 k .equ tmp_im+1 prcount .equ k+1 celnum .equ prcount+1 delta .equ celnum+1 celdist .equ delta+1 celcount.equ celdist+1 pairnum .equ celcount+1 log2_N .equ pairnum+1 N_1 .equ log2_N+1 cout .equ 0C305 .macro pop pla sta %1 pla sta %1+1 .endm .macro push lda %1+1 pha lda %1 pha .endm .proc byte_fft, 5 pop return pop scalfac pop sign pop N pop imag pop real ; pre-transform bit swap lda #0FF ; -1 sta log2_N lda N sta i sta N_1 ; useful later dec N_1 lda N+1 sta j $1 lsr j ; find power of 2 ror i inc log2_N bcc $1 ldy #1 bitrev lda #0 sta j tya clc ldx log2_N $1 ror a rol j dex bne $1 cpy j bmi $2 sty i lda (real),y pha lda (imag),y pha ldy j lda (real),y pha lda (imag),y ldy i sta (imag),y pla sta (real),y ldy j pla sta (imag),y pla sta (real),y ldy i $2 iny cpy N_1 bne bitrev lda cosadr sta costab lda cosadr+1 sta costab+1 lda #0 tay sta (scalfac),y iny sta (scalfac),y fft lda N+1 lsr a lda N ror a sta celnum lda #080 sta delta ldx #1 stx celdist stx pairnum npass jsr scale lda celnum sta celcount lda #0 sta i ncell ldx #0 stx k ldx pairnum nc1 lda i clc adc celdist sta j stx prcount ldy k lda (costab),y sta icos lda sign bpl $2 tya clc adc #040 ; go forward 64 places in cos table to get -sine jmp $3 $2 tya sec sbc #040 ; go back 64 places in cos table to get +sine $3 tay lda (costab),y sta isin ldy j lda (real),y pha sta mplier lda icos sta micand jsr multply sta tmp_re ; tmp_re = real(j) * cos pla sta mplier lda isin sta micand jsr multply sta tmp_im ; tmp_im = real(j) * sign * -sin lda (imag),y pha sta mplier lda isin sta micand jsr multply clc adc tmp_re sta tmp_re ; tmp_re = real(j) * cos + imag(j) * sign * -sin pla sta mplier lda icos sta micand jsr multply sec sbc tmp_im sta tmp_im ; tmp_im = imag(j) * cos - real(j) * sign * -sin ldy i lda (imag),y pha clc adc tmp_im sta (imag),y ; imag(i) = imag(i) + tmp_im lda (real),y pha clc adc tmp_re sta (real),y ; real(i) = real(i) + tmp_re pla sec sbc tmp_re ldy j sta (real),y ; real(j) = real(i) - tmp_re pla sec sbc tmp_im sta (imag),y ; imag(j) = imag(i) - tmp_im lda k clc adc delta sta k inc i ldx prcount dex beq $1 jmp nc1 $1 lda i clc adc celdist sta i dec celcount beq np1 jmp ncell np1 lsr celnum beq exit asl pairnum asl celdist lsr delta jmp npass exit push return rts cosadr .word cosine cosine .byte 127., 127., 127., 127., 127., 127., 127., 126. .byte 126., 125., 124., 123., 122., 122., 121., 119. .byte 118., 117., 116., 114., 113., 111., 110., 108. .byte 106., 105., 103., 101., 99., 97., 95., 93. .byte 91., 88., 86., 84., 81., 79., 76., 74. .byte 71., 68., 66., 63., 60., 58., 55., 52. .byte 49., 46., 43., 40., 37., 34., 31., 28. .byte 25., 22., 19., 16., 13., 9., 6., 3. .byte 0., -3., -6., -9., -13., -16., -19., -22. .byte -25., -28., -31., -34., -37., -40., -43., -46. .byte -49., -52., -55., -58., -60., -63., -66., -68. .byte -71., -74., -76., -79., -81., -84., -86., -88. .byte -91., -93., -95., -97., -99., -101., -103., -105. .byte -106., -108., -110., -111., -113., -114., -116., -117. .byte -118., -119., -121., -122., -122., -123., -124., -125. .byte -126., -126., -127., -127., -127., -128., -128., -128. .byte -128., -128., -128., -128., -127., -127., -127., -126. .byte -126., -125., -124., -123., -122., -122., -121., -119. .byte -118., -117., -116., -114., -113., -111., -110., -108. .byte -106., -105., -103., -101., -99., -97., -95., -93. .byte -91., -88., -86., -84., -81., -79., -76., -74. .byte -71., -68., -66., -63., -60., -58., -55., -52. .byte -49., -46., -43., -40., -37., -34., -31., -28. .byte -25., -22., -19., -16., -13., -9., -6., -3. .byte 0., 3., 6., 9., 13., 16., 19., 22. .byte 25., 28., 31., 34., 37., 40., 43., 46. .byte 49., 52., 55., 58., 60., 63., 66., 68. .byte 71., 74., 76., 79., 81., 84., 86., 88. .byte 91., 93., 95., 97., 99., 101., 103., 105. .byte 106., 108., 110., 111., 113., 114., 116., 117. .byte 118., 119., 121., 122., 122., 123., 124., 125. .byte 126., 126., 127., 127., 127., 127., 127., 127. multply lda #0 sta mplier+1 sta micand+1 ; clear MSB's sta result sta result+1 lda micand beq $9 bpl $1 lda #0FF sta micand+1 $1 lda mplier beq $9 bpl $2 lda #0FF sta mplier+1 $2 ldx #0F $3 lsr mplier+1 ror mplier bcc $4 lda micand clc adc result sta result lda micand+1 adc result+1 sta result+1 $4 asl micand rol micand+1 dex bne $3 $9 lda result+1 rol result rol a rts scale ldy #0 $2 lda (real),y beq $1 cmp #0C0 bpl $1 cmp #040 bmi $1 jmp shift lda (imag),y beq $1 cmp #0C0 bpl $1 cmp #040 bmi $1 jmp shift $1 iny cpy N bne $2 rts shift ldy #0 lda (scalfac),y clc adc #1 sta (scalfac),y $3 lda (real),y clc adc #080 lsr a sec sbc #040 sta (real),y lda (imag),y clc adc #080 lsr a sec sbc #040 sta (imag),y iny cpy N bne $3 rts .end
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