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C---------------------------------------------------------- |
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subroutine graytobin(cg,cb,n) |
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|
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c convert word of length n |
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c from Gray code Cg[0...n-1] |
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c to binary code Cb[0...n-1] |
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c 4 bits per time |
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c D.Campana - Jan. 2005 |
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C---------------------------------------------------------- |
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IMPLICIT NONE |
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|
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integer n, bit, bi |
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integer cg,cb |
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integer*1 a,b |
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integer*1 i,j,n4 |
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integer nby4,cgby4(8),cbby4(8) |
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c |
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c devo separare la parola nelle sue componenti da 4 bit |
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c ossia (0-3, 4-7, 8-11, 12-15) |
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c |
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|
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cb=0 |
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do i=1,8 |
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cgby4(i)=0 ! componenti da 4 bit in Gray |
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cbby4(i)=0 ! componenti da 4 bit in binario |
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enddo |
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nby4 = n/4 |
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|
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do i=1,nby4 |
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do j=1,4 |
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n4= (i-1)*4+j |
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bi = ibits(cg,n4-1,1) |
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if(bi.eq.1)cgby4(i)=ibset(cgby4(i),j-1) |
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enddo |
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enddo |
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c |
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do i=1,nby4 |
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bi = ibits(cgby4(i),3,1) |
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if(bi.eq.1) cbby4(i) = ibset(cbby4(i),3) |
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c |
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do bit=2,0,-1 |
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bi=0 |
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a=ibits(cgby4(i),bit,1) |
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b=ibits(cbby4(i),bit+1,1) |
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if(((a.eq.1).and.(b.eq.0)).or.((a.eq.0).and.(b.eq.1)))bi=1 |
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if(bi.eq.1)cbby4(i)=ibset(cbby4(i),bit) |
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enddo |
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enddo |
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c |
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do i=1,nby4 |
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do j=1,4 |
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n4= (i-1)*4+j |
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bi=ibits(cbby4(i),j-1,1) |
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if(bi.eq.1)cb=ibset(cb,n4-1) |
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enddo |
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enddo |
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c |
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return |
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end |
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