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https://github.com/saitohirga/WSJT-X.git
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Eliminate redundancies from the calculation of sequence correlations.
This commit is contained in:
Steven Franke
parent
ca0804450b
commit
1b59d9dc8c
@ -5,9 +5,9 @@ subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,nsync_qual,
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complex cd(0:NN*nss-1)
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complex cs(0:3,NN)
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complex csymb(nss)
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complex, allocatable, save :: c1(:,:) ! ideal waveforms, 20 samples per symbol, 4 tones
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complex, allocatable, save :: ci(:,:) ! ideal waveforms, 20 samples per symbol, 4 tones
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complex cp(0:3) ! accumulated phase shift over symbol types 0:3
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complex csum,cterm
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complex c1(4,8),c2(16,4),c4(256,2),c8(655356),cterm
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integer isyncword1(0:7),isyncword2(0:7)
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integer graymap(0:3)
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integer ip(1)
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@ -25,9 +25,9 @@ subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,nsync_qual,
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data first/.true./,nss0/-1/
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save first,one,cp,nss0
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if(nss.ne.nss0 .and. allocated(c1)) deallocate(c1)
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if(nss.ne.nss0 .and. allocated(ci)) deallocate(ci)
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if(first .or. nss.ne.nss0) then
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allocate(c1(nss,0:3))
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allocate(ci(nss,0:3))
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one=.false.
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do i=0,65535
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do j=0,15
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@ -40,7 +40,7 @@ subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,nsync_qual,
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dp=(itone-1.5)*dphi
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phi=0.0
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do j=1,nss
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c1(j,itone)=cmplx(cos(phi),sin(phi))
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ci(j,itone)=cmplx(cos(phi),sin(phi))
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phi=mod(phi+dp,twopi)
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enddo
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cp(itone)=cmplx(cos(phi),sin(phi))
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@ -52,7 +52,7 @@ subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,nsync_qual,
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i1=(k-1)*NSS
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csymb=cd(i1:i1+NSS-1)
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do itone=0,3
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cs(itone,k)=sum(csymb*conjg(c1(:,itone)))
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cs(itone,k)=sum(csymb*conjg(ci(:,itone)))
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enddo
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s4(0:3,k)=abs(cs(0:3,k))**2
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enddo
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@ -85,49 +85,85 @@ subroutine get_fst4_bitmetrics(cd,nss,hmod,nmax,nhicoh,bitmetrics,s4,nsync_qual,
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return
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endif
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call timer('seqcorrs',0)
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bitmetrics=0.0
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do nseq=1,nmax !Try coherent sequences of 1,2,3,4 or 1,2,4,8 symbols
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if(nseq.eq.1) nsym=1
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if(nseq.eq.2) nsym=2
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if(nhicoh.eq.0) then
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if(nseq.eq.3) nsym=3
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if(nseq.eq.4) nsym=4
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else
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if(nseq.eq.3) nsym=4
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if(nseq.eq.4) nsym=8
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endif
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nt=4**nsym
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do ks=1,NN-nsym+1,nsym
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! Process the frame in 8-symbol chunks. Use 1-symbol correlations to calculate
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! 2-symbol correlations. Then use 2-symbol correlations to calculate 4-symbol
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! correlations. Finally, use 4-symbol correlations to calculate 8-symbol corrs.
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! This eliminates redundant calculations.
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do k=1,NN,8
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do m=1,8 ! do 4 1-symbol correlations for each of 8 symbs
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s2=0
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do i=0,nt-1
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csum=0
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! cterm=1 ! hmod.ne.1
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term=1
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do j=0,nsym-1
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ntone=mod(i/4**(nsym-1-j),4)
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csum=csum+cs(graymap(ntone),ks+j)*term
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term=-term
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! csum=csum+cs(graymap(ntone),ks+j)*cterm ! hmod.ne.1
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! cterm=cterm*conjg(cp(graymap(ntone))) ! hmod.ne.1
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enddo
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s2(i)=abs(csum)
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do n=1,4
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c1(n,m)=cs(graymap(n-1),k+m-1)
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s2(n-1)=abs(c1(n,m))
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enddo
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ipt=1+(ks-1)*2
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if(nsym.eq.1) ibmax=1
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if(nsym.eq.2) ibmax=3
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if(nsym.eq.3) ibmax=5
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if(nsym.eq.4) ibmax=7
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if(nsym.eq.8) ibmax=15
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do ib=0,ibmax
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bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - &
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maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib))
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ipt=(k-1)*2+2*(m-1)+1
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do ib=0,1
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bm=maxval(s2(0:3),one(0:3,1-ib)) - &
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maxval(s2(0:3),.not.one(0:3,1-ib))
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if(ipt+ib.gt.2*NN) cycle
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bitmetrics(ipt+ib,nseq)=bm
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bitmetrics(ipt+ib,1)=bm
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enddo
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enddo
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do m=1,4 ! do 16 2-symbol correlations for each of 4 2-symbol groups
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s2=0
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do i=1,4
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do j=1,4
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is=(i-1)*4+j
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c2(is,m)=c1(i,2*m-1)-c1(j,2*m)
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s2(is-1)=abs(c2(is,m))
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enddo
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enddo
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ipt=(k-1)*2+4*(m-1)+1
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do ib=0,3
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bm=maxval(s2(0:15),one(0:15,3-ib)) - &
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maxval(s2(0:15),.not.one(0:15,3-ib))
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if(ipt+ib.gt.2*NN) cycle
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bitmetrics(ipt+ib,2)=bm
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enddo
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enddo
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do m=1,2 ! do 256 4-symbol corrs for each of 2 4-symbol groups
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s2=0
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do i=1,16
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do j=1,16
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is=(i-1)*16+j
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c4(is,m)=c2(i,2*m-1)+c2(j,2*m)
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s2(is-1)=abs(c4(is,m))
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enddo
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enddo
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ipt=(k-1)*2+8*(m-1)+1
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do ib=0,7
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bm=maxval(s2(0:255),one(0:255,7-ib)) - &
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maxval(s2(0:255),.not.one(0:255,7-ib))
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if(ipt+ib.gt.2*NN) cycle
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bitmetrics(ipt+ib,3)=bm
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enddo
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enddo
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s2=0 ! do 65536 8-symbol correlations for the entire group
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do i=1,256
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do j=1,256
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is=(i-1)*256+j
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c8(is)=c4(i,1)+c4(j,2)
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s2(is-1)=abs(c8(is))
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enddo
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enddo
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ipt=(k-1)*2+1
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do ib=0,15
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bm=maxval(s2(0:65535),one(0:65535,15-ib)) - &
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maxval(s2(0:65535),.not.one(0:65535,15-ib))
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if(ipt+ib.gt.2*NN) cycle
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bitmetrics(ipt+ib,4)=bm
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enddo
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enddo
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call timer('seqcorrs',1)
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hbits=0
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