📄 fft16_mac.s.list
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0x000000f0: 48c6 ext.l d6 ;d6 = bi0
0x000000f2: 48c7 ext.l d7 ;d7 = bi1
0x000000f4: 2440 movea.l d0,a2 ;a2 = ar0
0x000000f6: 2641 movea.l d1,a3 ;a3 = ar1
0x000000f8: 2844 movea.l d4,a4 ;a4 = ai0
0x000000fa: 2a45 movea.l d5,a5 ;a5 = ai1
0x000000fc: d082 add.l d2,d0 ;xr0 = ar0 + br0
0x000000fe: 30c0 move.w d0,(a0)+
0x00000100: d287 add.l d7,d1 ;xr1 = ar1 + bi1
0x00000102: 30c1 move.w d1,(a0)+
0x00000104: 95c2 suba.l d2,a2 ;yr0 = ar0 - br0
0x00000106: 30ca move.w a2,(a0)+
0x00000108: 97c7 suba.l d7,a3 ;yr1 = ar1 - bi1
0x0000010a: 30cb move.w a3,(a0)+
0x0000010c: d886 add.l d6,d4 ;xi0 = ai0 + bi0
0x0000010e: 32c4 move.w d4,(a1)+
0x00000110: 9a83 sub.l d3,d5 ;xi1 = ai1 - br1
0x00000112: 32c5 move.w d5,(a1)+
0x00000114: 99c6 suba.l d6,a4 ;yi0 = ai0 - bi0
0x00000116: 32cc move.w a4,(a1)+
0x00000118: dbc3 adda.l d3,a5 ;yi1 = ai1 + br1
0x0000011a: 32cd move.w a5,(a1)+
0x0000011c: 528e addq.l #1,a6 ;
0x0000011e: bdfc00000080 cmpa.l #128,a6
0x00000124: 65a2 bcs.b second_stage
0x00000126: 203c00000040 move.l #64,d0 ;FFT for complex values
0x0000012c: 2f400040 move.l d0,(64,a7) ;starts from 3-rd stage
0x00000130: 7002 moveq.l #2,d0
0x00000132: 2f400044 move.l d0,(68,a7) ;stage loop counter (starts from 3rd stage)
0x00000136: 2a7c00000008 movea.l #8,a5 ;a5 contains the number of butterflies
;per one sub DFT multiplied
;by 2 (the size of values)
0x0000013c: 2c3c00000200 move.l #512,d6 ;step in the table of twiddle factors
;(multiplied by 2 because of the size
;of coefficients)
0x00000142: 2c7c00000000 movea.l #0,a6 ;counter for butterfly loop
;from MSW to LSW to store it correctly
;into the memory)
0x00000148: a93c00000070 move.l #0x00000070,MACSR
0x0000014e: 4282 clr.l d2
0x00000150: 4287 clr.l d7
next_stage ;start of stages loop
0x00000152: 7000 moveq.l #0,d0
0x00000154: 2f40003c move.l d0,(60,a7) ;sub DFT loop counter
0x00000158: 4cef0300004c movem.l (76,a7),a0-a1 ;a0 points to ar0, a1 points to ai0
0x0000015e: 2448 movea.l a0,a2
0x00000160: 2649 movea.l a1,a3
0x00000162: d5cd adda.l a5,a2 ;a2 points to br0
0x00000164: d7cd adda.l a5,a3 ;a3 points to bi0
next_subDFT ;start of sub DFTs loop
0x00000166: 287c00000000 movea.l #TF_table,a4 ;a4 points to the beginning of the table
next_bf ;start of butterflies loop
0x0000016c: 2014 move.l (a4),d0 ;wr -> MSW of d0
;wi -> LSW of d0
0x0000016e: 3410 move.w (a0),d2 ;ar -> MSW of d2
0x00000170: 2812 move.l (a2),d4 ;br -> MSW of d4
0x00000172: 3e11 move.w (a1),d7
0x00000174: a13c00000000 move.l #0,ACC
0x0000017a: aa9343c0 msacl.w d0.u,d4.u,<<,(a3),d5 ;ar-br*wr -> ACC, bi -> MSW of d5
0x0000017e: aa000380 msac.w d0.l,d5.u,<<,ACC ;ar-br*wr-bi*wi = xr -> ACC, ai -> MSW of d7
0x00000182: a183 move.l ACC,d3
0x00000184: d682 add.l d2,d3 ;ar -> ACC
0x00000186: 30c3 move.w d3,(a0)+ ;xr -> memory
0x00000188: d482 add.l d2,d2 ;2*ar -> d2
0x0000018a: 9483 sub.l d3,d2 ;2*ar-xr = yr -> d2
0x0000018c: 34c2 move.w d2,(a2)+ ;yr -> memory
0x0000018e: a13c00000000 move.l #0,ACC
0x00000194: a8000280 mac.w d0.l,d4.u,<< ;ai+br*wi -> ACC, ar -> MSW of d2
0x00000198: aa0003c0 msac.w d0.u,d5.u,<< ;ai+br*wi-bi*wr = xi -> ACC, br -> MSW of d4
0x0000019c: a183 move.l ACC,d3
0x0000019e: d687 add.l d7,d3
0x000001a0: 32c3 move.w d3,(a1)+ ;xi -> memory
0x000001a2: de87 add.l d7,d7 ;2*ai -> d7
0x000001a4: 9e83 sub.l d3,d7 ;2*ai-xi = yi -> d7
0x000001a6: 36c7 move.w d7,(a3)+ ;yi -> memory
0x000001a8: d9c6 adda.l d6,a4 ;modify pointer to the twiddle factor
;for the next butterfly
0x000001aa: 548e addq.l #2,a6
0x000001ac: bdcd cmpa.l a5,a6
0x000001ae: 65bc bcs.b next_bf ;end of butterflies loop
;of the current sub DFT
0x000001b0: 2c7c00000000 move.l #0,a6
0x000001b6: d1cd adda.l a5,a0 ;a0 - a3 point to the input values
0x000001b8: d3cd adda.l a5,a1 ;for the first butterfly
0x000001ba: d5cd adda.l a5,a2 ;of the next sub DFT
0x000001bc: d7cd adda.l a5,a3
0x000001be: 202f003c move.l (60,a7),d0
0x000001c2: 5280 addq.l #1,d0
0x000001c4: 2f40003c move.l d0,(60,a7) ;increment sub DFT loop counter
0x000001c8: b0af0040 cmp.l (64,a7),d0 ;compare sub DFT loop counter with
;the number of sub DFTs on this stage
0x000001cc: 6500ff98 bcs.w next_subDFT ;end of sub DFTs loop
0x000001d0: 7000 moveq.l #0,d0
0x000001d2: 2f40003c move.l d0,(60,a7) ;store 0 to the sub DFT loop counter
0x000001d6: dbcd adda.l a5,a5 ;multiply contents of a5 (the number of
;butterflies per one sub DFT) by 2 for the
;next stage
0x000001d8: e28e lsr.l #1,d6 ;divide step in the table of twiddle
;factors by 2
0x000001da: 202f0040 move.l (64,a7),d0 ;divide the number of sub DFTs for the
0x000001de: e288 lsr.l #1,d0 ;next stage by 2
0x000001e0: 2f400040 move.l d0,(64,a7)
0x000001e4: 202f0044 move.l (68,a7),d0 ;increment stage loop counter
0x000001e8: 5280 addq.l #1,d0
0x000001ea: 2f400044 move.l d0,(68,a7)
0x000001ee: 0c8000000009 cmpi.l #9,d0
0x000001f4: 6500ff5c bcs.w next_stage ;end of stage loop
;even/odd frequency domain decomposition
;Corresponding C code:
;nm1=smpl_num-1;
;nd2=smpl_num>>1;
;n4=(smpl_num>>2);
;for (i=1;i<n4;i++){
; im=nd2-i;
; ip2=i+nd2;
; ipm=im+nd2;
;
; ReX[ip2]=(ImX[i]+ImX[im])/2;
; ReX[ipm]=ReX[ip2];
;
; ImX[ip2]=(ReX[im]-ReX[i])/2;
; ImX[ipm]=-ImX[ip2];
;
; ReX[i]=(ReX[i]+ReX[im])/2;
; ReX[im]=ReX[i];
;
; ImX[i]=(ImX[i]-ImX[im])/2;
; ImX[im]=-ImX[i];
;}
;n34=(smpl_num*3)>>2;
;ReX[n34]=ImX[n4];
;ReX[nd2]=ImX[0];
;ImX[n34]=0;
;ImX[nd2]=0;
;ImX[n4]=0;
;ImX[0]=0;
0x000001f8: 4cef0300004c movem.l (76,a7),a0/a1 ;even/odd frequency domain decomposition
0x000001fe: 45e80002 lea (2,a0),a2
0x00000202: 47e90002 lea (2,a1),a3
0x00000206: 49e80400 lea (1024,a0),a4
0x0000020a: 4be90400 lea (1024,a1),a5
0x0000020e: 4de80402 lea (1026,a0),a6
0x00000212: 203c00000402 move.l #1026,d0
0x00000218: 2c3c000007fe move.l #2046,d6
0x0000021e: 3613 adjust move.w (a3),d3 ;d3 = ImX[i]
0x00000220: 48c3 ext.l d3
0x00000222: 2203 move.l d3,d1 ;d1 = ImX[i]
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