mod2entry *mod2sparse_find
( mod2sparse *m,
int row,
int col
)
{
mod2entry *re, *ce;
if (row<0 || row>=mod2sparse_rows(m) || col<0 || col>=mod2sparse_cols(m))
{ fprintf(stderr,"mod2sparse_find: row or column index out of bounds\n");
exit(1);
}
/* Check last entries in row. */
re = mod2sparse_last_in_row(m,row);
if (mod2sparse_at_end(re) || mod2sparse_col(re)<col)
{ return 0;
}
if (mod2sparse_col(re)==col)
{ return re;
}
#ifndef SPARSE_MATRIX_OPT_FOR_LDPC_STAIRCASE
ce = mod2sparse_last_in_col(m,col);
if (mod2sparse_at_end(ce) || mod2sparse_row(ce)<row)
{ return 0;
}
if (mod2sparse_row(ce)==row)
{ return ce;
}
#endif
/* Search row and column in parallel, from the front. */
re = mod2sparse_first_in_row(m,row);
ce = mod2sparse_first_in_col(m,col);
for (;;)
{
if (mod2sparse_at_end(re) || mod2sparse_col(re)>col)
{ return 0;
}
if (mod2sparse_col(re)==col)
{ return re;
}
if (mod2sparse_at_end(ce) || mod2sparse_row(ce)>row)
{ return 0;
}
if (mod2sparse_row(ce)==row)
{ return ce;
}
re = mod2sparse_next_in_row(re);
ce = mod2sparse_next_in_col(ce);
}
}
void mod2sparse_add
( mod2sparse *m1, /* Left operand of add */
mod2sparse *m2, /* Right operand of add */
mod2sparse *r /* Place to store result of add */
)
{
mod2entry *e1, *e2;
int i;
if (mod2sparse_rows(m1)!=mod2sparse_rows(r)
|| mod2sparse_cols(m1)!=mod2sparse_cols(r)
|| mod2sparse_rows(m2)!=mod2sparse_rows(r)
|| mod2sparse_cols(m2)!=mod2sparse_cols(r))
{ fprintf(stderr,"mod2sparse_add: Matrices have different dimensions\n");
exit(1);
}
if (r==m1 || r==m2)
{ fprintf(stderr,
"mod2sparse_add: Result matrix is the same as one of the operands\n");
exit(1);
}
mod2sparse_clear(r);
for (i = 0; i<mod2sparse_rows(r); i++)
{
e1 = mod2sparse_first_in_row(m1,i);
e2 = mod2sparse_first_in_row(m2,i);
while (!mod2sparse_at_end(e1) && !mod2sparse_at_end(e2))
{
if (mod2sparse_col(e1)==mod2sparse_col(e2))
{ e1 = mod2sparse_next_in_row(e1);
e2 = mod2sparse_next_in_row(e2);
}
else if (mod2sparse_col(e1)<mod2sparse_col(e2))
{ mod2sparse_insert(r,i,mod2sparse_col(e1));
e1 = mod2sparse_next_in_row(e1);
}
else
{ mod2sparse_insert(r,i,mod2sparse_col(e2));
e2 = mod2sparse_next_in_row(e2);
}
}
while (!mod2sparse_at_end(e1))
{ mod2sparse_insert(r,i,mod2sparse_col(e1));
e1 = mod2sparse_next_in_row(e1);
}
while (!mod2sparse_at_end(e2))
{ mod2sparse_insert(r,i,mod2sparse_col(e2));
e2 = mod2sparse_next_in_row(e2);
}
}
}
void mod2sparse_transpose
( mod2sparse *m, /* Matrix to compute transpose of (left unchanged) */
mod2sparse *r /* Result of transpose operation */
)
{
mod2entry *e;
int i;
if (mod2sparse_rows(m)!=mod2sparse_cols(r)
|| mod2sparse_cols(m)!=mod2sparse_rows(r))
{ fprintf(stderr,
"mod2sparse_transpose: Matrices have incompatible dimensions\n");
exit(1);
}
if (r==m)
{ fprintf(stderr,
"mod2sparse_transpose: Result matrix is the same as the operand\n");
exit(1);
}
mod2sparse_clear(r);
for (i = 0; i<mod2sparse_rows(m); i++)
{
e = mod2sparse_first_in_row(m,i);
while (!mod2sparse_at_end(e))
{ mod2sparse_insert(r,mod2sparse_col(e),i);
e = mod2sparse_next_in_row(e);
}
}
}
double expected_parity_errors
( mod2sparse *H, /* Parity check matrix */
double *bpr /* Bit probabilities */
)
{
mod2entry *f;
double ee, p;
int M, i, j;
M = mod2sparse_rows(H);
ee = 0;
for (i = 0; i<M; i++)
{ p = 0;
for (f = mod2sparse_first_in_row(H,i);
!mod2sparse_at_end(f);
f = mod2sparse_next_in_row(f))
{ j = mod2sparse_col(f);
p = p * (1-bpr[j]) + (1-p) * bpr[j];
}
ee += p;
}
return ee;
}
int mod2sparse_equal
( mod2sparse *m1,
mod2sparse *m2
)
{
mod2entry *e1, *e2;
int i;
if (mod2sparse_rows(m1)!=mod2sparse_rows(m2)
|| mod2sparse_cols(m1)!=mod2sparse_cols(m2))
{ fprintf(stderr,"mod2sparse_equal: Matrices have different dimensions\n");
exit(1);
}
for (i = 0; i<mod2sparse_rows(m1); i++)
{
e1 = mod2sparse_first_in_row(m1,i);
e2 = mod2sparse_first_in_row(m2,i);
while (!mod2sparse_at_end(e1) && !mod2sparse_at_end(e2))
{
if (mod2sparse_col(e1)!=mod2sparse_col(e2))
{ return 0;
}
e1 = mod2sparse_next_in_row(e1);
e2 = mod2sparse_next_in_row(e2);
}
if (!mod2sparse_at_end(e1) || !mod2sparse_at_end(e2))
{ return 0;
}
}
return 1;
}
int mod2sparse_write
( FILE *f,
mod2sparse *m
)
{
mod2entry *e;
int i;
intio_write(f,m->n_rows);
if (ferror(f)) return 0;
intio_write(f,m->n_cols);
if (ferror(f)) return 0;
for (i = 0; i<mod2sparse_rows(m); i++)
{
e = mod2sparse_first_in_row(m,i);
if (!mod2sparse_at_end(e))
{
intio_write (f, -(i+1));
if (ferror(f)) return 0;
while (!mod2sparse_at_end(e))
{
intio_write (f, mod2sparse_col(e)+1);
if (ferror(f)) return 0;
e = mod2sparse_next_in_row(e);
}
}
}
intio_write(f,0);
if (ferror(f)) return 0;
return 1;
}
void mod2sparse_add_row
( mod2sparse *m1, /* Matrix containing row to add to */
int row1, /* Index in this matrix of row to add to */
mod2sparse *m2, /* Matrix containing row to add from */
int row2 /* Index in this matrix of row to add from */
)
{
mod2entry *f1, *f2, *ft;
if (mod2sparse_cols(m1)<mod2sparse_cols(m2))
{ fprintf (stderr,
"mod2sparse_add_row: row added to is shorter than row added from\n");
exit(1);
}
if (row1<0 || row1>=mod2sparse_rows(m1)
|| row2<0 || row2>=mod2sparse_rows(m2))
{ fprintf (stderr,"mod2sparse_add_row: row index out of range\n");
exit(1);
}
f1 = mod2sparse_first_in_row(m1,row1);
f2 = mod2sparse_first_in_row(m2,row2);
while (!mod2sparse_at_end(f1) && !mod2sparse_at_end(f2))
{ if (mod2sparse_col(f1)>mod2sparse_col(f2))
{ mod2sparse_insert(m1,row1,mod2sparse_col(f2));
f2 = mod2sparse_next_in_row(f2);
}
else
{ ft = mod2sparse_next_in_row(f1);
if (mod2sparse_col(f1)==mod2sparse_col(f2))
{ mod2sparse_delete(m1,f1);
f2 = mod2sparse_next_in_row(f2);
}
f1 = ft;
}
}
while (!mod2sparse_at_end(f2))
{ mod2sparse_insert(m1,row1,mod2sparse_col(f2));
f2 = mod2sparse_next_in_row(f2);
}
}
void mod2sparse_print
( FILE *f,
mod2sparse *m
)
{
int rdigits, cdigits;
mod2entry *e;
int i;
rdigits = mod2sparse_rows(m)<=10 ? 1
: mod2sparse_rows(m)<=100 ? 2
: mod2sparse_rows(m)<=1000 ? 3
: mod2sparse_rows(m)<=10000 ? 4
: mod2sparse_rows(m)<=100000 ? 5
: 6;
cdigits = mod2sparse_cols(m)<=10 ? 1
: mod2sparse_cols(m)<=100 ? 2
: mod2sparse_cols(m)<=1000 ? 3
: mod2sparse_cols(m)<=10000 ? 4
: mod2sparse_cols(m)<=100000 ? 5
: 6;
for (i = 0; i<mod2sparse_rows(m); i++)
{
fprintf(f,"%*d:",rdigits,i);
e = mod2sparse_first_in_row(m,i);
while (!mod2sparse_at_end(e))
{ fprintf(f," %*d",cdigits,mod2sparse_col(e));
e = mod2sparse_next_in_row(e);
}
fprintf(f,"\n");
}
}
int mod2sparse_decomp
( mod2sparse *A, /* Input matrix, M by N */
int K, /* Size of sub-matrix to find LU decomposition of */
mod2sparse *L, /* Matrix in which L is stored, M by K */
mod2sparse *U, /* Matrix in which U is stored, K by N */
int *rows, /* Array where row indexes are stored, M long */
int *cols, /* Array where column indexes are stored, N long */
mod2sparse_strategy strategy, /* Strategy to follow in picking rows/columns */
int abandon_number, /* Number of columns to abandon at some point */
int abandon_when /* When to abandon these columns */
)
{
int *rinv=NULL, *cinv=NULL, *acnt=NULL, *rcnt=NULL;
mod2sparse *B=NULL;
int M, N;
mod2entry *e=NULL, *f=NULL, *fn=NULL, *e2=NULL;
int i=0, j=0, k=0, cc=0, cc2=0, cc3=0, cr2=0, pr=0;
int found, nnf;
M = mod2sparse_rows(A);
N = mod2sparse_cols(A);
if (mod2sparse_cols(L)!=K || mod2sparse_rows(L)!=M
|| mod2sparse_cols(U)!=N || mod2sparse_rows(U)!=K)
{ fprintf (stderr,
"mod2sparse_decomp: Matrices have incompatible dimensions\n");
exit(1);
}
if (abandon_number>N-K)
{ fprintf(stderr,"Trying to abandon more columns than allowed\n");
exit(1);
}
rinv = (int*)chk_alloc (M, sizeof *rinv);
cinv = (int*)chk_alloc (N, sizeof *cinv);
if (abandon_number>0)
{
acnt = (int*)chk_alloc (M+1, sizeof *acnt);
}
if (strategy==Mod2sparse_minprod)
{
rcnt = (int*)chk_alloc (M, sizeof *rcnt);
}
mod2sparse_clear(L);
mod2sparse_clear(U);
/* Copy A to B. B will be modified, then discarded. */
B = mod2sparse_allocate(M,N);
mod2sparse_copy(A,B);
/* Count 1s in rows of B, if using minprod strategy. */
if (strategy==Mod2sparse_minprod)
{ for (i = 0; i<M; i++)
{ rcnt[i] = mod2sparse_count_row(B,i);
}
}
/* Set up initial row and column choices. */
for (i = 0; i<M; i++) rows[i] = rinv[i] = i;
for (j = 0; j<N; j++) cols[j] = cinv[j] = j;
/* Find L and U one column at a time. */
nnf = 0;
for (i = 0; i<K; i++)
{
/* Choose the next row and column of B. */
switch (strategy)
{
case Mod2sparse_first:
{
found = 0;
for (k = i; k<N; k++)
{ e = mod2sparse_first_in_col(B,cols[k]);
while (!mod2sparse_at_end(e))
{ if (rinv[mod2sparse_row(e)]>=i)
{ found = 1;
goto out_first;
}
e = mod2sparse_next_in_col(e);
}
}
out_first:
break;
}
case Mod2sparse_mincol:
{
found = 0;
for (j = i; j<N; j++)
{ cc2 = mod2sparse_count_col(B,cols[j]);
if (!found || cc2<cc)
{ e2 = mod2sparse_first_in_col(B,cols[j]);
while (!mod2sparse_at_end(e2))
{ if (rinv[mod2sparse_row(e2)]>=i)
{ found = 1;
cc = cc2;
e = e2;
k = j;
break;
}
e2 = mod2sparse_next_in_col(e2);
}
}
}
break;
}
case Mod2sparse_minprod:
{
found = 0;
for (j = i; j<N; j++)
{ cc2 = mod2sparse_count_col(B,cols[j]);
e2 = mod2sparse_first_in_col(B,cols[j]);
while (!mod2sparse_at_end(e2))
{ if (rinv[mod2sparse_row(e2)]>=i)
{ cr2 = rcnt[mod2sparse_row(e2)];
if (!found || cc2==1 || (cc2-1)*(cr2-1)<pr)
{ found = 1;
pr = cc2==1 ? 0 : (cc2-1)*(cr2-1);
e = e2;
k = j;
}
}
e2 = mod2sparse_next_in_col(e2);
}
}
break;
}
default:
{ fprintf(stderr,"mod2sparse_decomp: Unknown stategy\n");
exit(1);
}
}
if (!found)
{ nnf += 1;
}
/* Update 'rows' and 'cols'. Looks at 'k' and 'e' found above. */
if (found)
{
if (cinv[mod2sparse_col(e)]!=k) abort();
cols[k] = cols[i];
cols[i] = mod2sparse_col(e);
cinv[cols[k]] = k;
cinv[cols[i]] = i;
k = rinv[mod2sparse_row(e)];
if (k<i) abort();
rows[k] = rows[i];
rows[i] = mod2sparse_row(e);
rinv[rows[k]] = k;
rinv[rows[i]] = i;
}
/* Update L, U, and B. */
f = mod2sparse_first_in_col(B,cols[i]);
while (!mod2sparse_at_end(f))
{
fn = mod2sparse_next_in_col(f);
k = mod2sparse_row(f);
if (rinv[k]>i)
{ mod2sparse_add_row(B,k,B,mod2sparse_row(e));
if (strategy==Mod2sparse_minprod)
{ rcnt[k] = mod2sparse_count_row(B,k);
}
mod2sparse_insert(L,k,i);
}
else if (rinv[k]<i)
{ mod2sparse_insert(U,rinv[k],cols[i]);
}
else
{ mod2sparse_insert(L,k,i);
mod2sparse_insert(U,i,cols[i]);
}
f = fn;
}
/* Get rid of all entries in the current column of B, just to save space. */
for (;;)
{ f = mod2sparse_first_in_col(B,cols[i]);
if (mod2sparse_at_end(f)) break;
mod2sparse_delete(B,f);
}
/* Abandon columns of B with lots of entries if it's time for that. */
if (abandon_number>0 && i==abandon_when)
{
for (k = 0; k<M+1; k++)
{ acnt[k] = 0;
}
for (j = 0; j<N; j++)
{ k = mod2sparse_count_col(B,j);
acnt[k] += 1;
}
cc = abandon_number;
k = M;
while (acnt[k]<cc)
{ cc -= acnt[k];
k -= 1;
if (k<0) abort();
}
cc2 = 0;
for (j = 0; j<N; j++)
{ cc3 = mod2sparse_count_col(B,j);
if (cc3>k || cc3==k && cc>0)
{ if (cc3==k) cc -= 1;
for (;;)
{ f = mod2sparse_first_in_col(B,j);
if (mod2sparse_at_end(f)) break;
mod2sparse_delete(B,f);
}
cc2 += 1;
}
}
if (cc2!=abandon_number) abort();
if (strategy==Mod2sparse_minprod)
{ for (j = 0; j<M; j++)
{ rcnt[j] = mod2sparse_count_row(B,j);
}
}
}
}
/* Get rid of all entries in the rows of L past row K, after reordering. */
for (i = K; i<M; i++)
{ for (;;)
{ f = mod2sparse_first_in_row(L,rows[i]);
if (mod2sparse_at_end(f)) break;
mod2sparse_delete(L,f);
}
}
mod2sparse_free(B);
free(rinv);
free(cinv);
if (strategy==Mod2sparse_minprod) free(rcnt);
if (abandon_number>0) free(acnt);
return nnf;
}
void mod2sparse_multiply
( mod2sparse *m1, /* Left operand of multiply */
mod2sparse *m2, /* Right operand of multiply */
mod2sparse *r /* Place to store result of multiply */
)
{
mod2entry *e1, *e2;
int i, j, b;
if (mod2sparse_cols(m1)!=mod2sparse_rows(m2)
|| mod2sparse_rows(m1)!=mod2sparse_rows(r)
|| mod2sparse_cols(m2)!=mod2sparse_cols(r))
{ fprintf (stderr,
"mod2sparse_multiply: Matrices have incompatible dimensions\n");
exit(1);
}
if (r==m1 || r==m2)
{ fprintf(stderr,
"mod2sparse_multiply: Result matrix is the same as one of the operands\n");
exit(1);
}
mod2sparse_clear(r);
for (i = 0; i<mod2sparse_rows(m1); i++)
{
if (mod2sparse_at_end(mod2sparse_first_in_row(m1,i)))
{ continue;
}
for (j = 0; j<mod2sparse_cols(m2); j++)
{
b = 0;
e1 = mod2sparse_first_in_row(m1,i);
e2 = mod2sparse_first_in_col(m2,j);
while (!mod2sparse_at_end(e1) && !mod2sparse_at_end(e2))
{
if (mod2sparse_col(e1)==mod2sparse_row(e2))
{ b ^= 1;
e1 = mod2sparse_next_in_row(e1);
e2 = mod2sparse_next_in_col(e2);
}
else if (mod2sparse_col(e1)<mod2sparse_row(e2))
{ e1 = mod2sparse_next_in_row(e1);
}
else
{ e2 = mod2sparse_next_in_col(e2);
}
}
if (b)
{ mod2sparse_insert(r,i,j);
}
}
}
}
mod2entry *mod2sparse_insert
( mod2sparse *m,
int row,
int col
)
{
#ifndef SPARSE_MATRIX_OPT_FOR_LDPC_STAIRCASE
mod2entry *re, *ce, *ne;
#else
mod2entry *re, *ce, *ne, *ce2;
#endif
if (row<0 || row>=mod2sparse_rows(m) || col<0 || col>=mod2sparse_cols(m))
{ fprintf(stderr,"mod2sparse_insert: row or column index out of bounds\n");
exit(1);
}
/* Find old entry and return it, or allocate new entry and insert into row. */
re = mod2sparse_last_in_row(m,row);
if (!mod2sparse_at_end(re) && mod2sparse_col(re)==col)
{ return re;
}
if (mod2sparse_at_end(re) || mod2sparse_col(re)<col)
{ re = re->right;
}
else
{
re = mod2sparse_first_in_row(m,row);
for (;;)
{
if (!mod2sparse_at_end(re) && mod2sparse_col(re)==col)
{ return re;
}
if (mod2sparse_at_end(re) || mod2sparse_col(re)>col)
{ break;
}
re = mod2sparse_next_in_row(re);
}
}
ne = alloc_entry(m);
ne->row = row;
ne->col = col;
ne->left = re->left;
ne->right = re;
ne->left->right = ne;
ne->right->left = ne;
/* Insert new entry into column. */
#ifndef SPARSE_MATRIX_OPT_FOR_LDPC_STAIRCASE
/* If we find an existing entry here,
the matrix must be garbled, since we didn't find it in the row. */
ce = mod2sparse_last_in_col(m,col);
if (!mod2sparse_at_end(ce) && mod2sparse_row(ce)==row)
{ fprintf(stderr,"mod2sparse_insert: Garbled matrix\n");
exit(1);
}
if (mod2sparse_at_end(ce) || mod2sparse_row(ce)<row)
{ ce = ce->down;
}
else
{
#else
ce2 = &(m->cols[col]);
#endif
ce = mod2sparse_first_in_col(m,col);
for (;;)
{
if (!mod2sparse_at_end(ce) && mod2sparse_row(ce)==row)
{ fprintf(stderr,"mod2sparse_insert: Garbled matrix\n");
exit(1);
}
if (mod2sparse_at_end(ce) || mod2sparse_row(ce)>row)
{ break;
}
#ifdef SPARSE_MATRIX_OPT_FOR_LDPC_STAIRCASE
ce2 = ce;
#endif
ce = mod2sparse_next_in_col(ce);
}
#ifndef SPARSE_MATRIX_OPT_FOR_LDPC_STAIRCASE
}
ne->up = ce->up;
ne->down = ce;
ne->up->down = ne;
ne->down->up = ne;
#else
ne->down = ce;
ce2->down = ne;
#endif
/* Return the new entry. */
return ne;
}
int mod2sparse_backward_sub
( mod2sparse *U, /* Matrix that is upper triangular after reordering */
int *cols, /* Array of indexes (from 0) of columns for new order */
char *y, /* Vector on right of equation */
char *z /* Place to store solution, also reordered */
)
{
int K, i, j, ii, b, d;
mod2entry *e;
K = mod2sparse_rows(U);
/* Make sure that U is upper-triangular, after column re-ordering. */
for (i = 0; i<K; i++)
{ ii = cols ? cols[i] : i;
e = mod2sparse_last_in_col(U,ii);
if (!mod2sparse_at_end(e) && mod2sparse_row(e)>i)
{ fprintf(stderr,
"mod2sparse_backward_sub: Matrix is not upper-triangular\n");
exit(1);
}
}
/* Solve system by backward substitution. */
for (i = K-1; i>=0; i--)
{
ii = cols ? cols[i] : i;
/* Look at bits in this row, forming inner product with partial
solution, and seeing if the diagonal is 1. */
d = 0;
b = 0;
for (e = mod2sparse_first_in_row(U,i);
!mod2sparse_at_end(e);
e = mod2sparse_next_in_row(e))
{
j = mod2sparse_col(e);
if (j==ii)
{ d = 1;
}
else
{ b ^= z[j];
}
}
/* Check for no solution if the diagonal isn't 1. */
if (!d && b!=y[i])
{ return 0;
}
/* Set bit of solution, zero if arbitrary. */
z[ii] = b^y[i];
}
return 1;
}
int mod2sparse_tunnel_sub
( mod2sparse *L, /* Matrix that is lower triangular after reordering */
int *rows, /* Array of indexes (from 0) of rows for new order */
char *x, /* Vector on right of equation, also reordered */
char *y /* Place to store solution */
)
{
int K, i, j, ii, b, d;
mod2entry *e;
K = mod2sparse_cols(L);
/* Make sure that L is lower-triangular, after row re-ordering. */
for (i = 0; i<K; i++)
{ ii = rows ? rows[i] : i;
e = mod2sparse_last_in_row(L,ii);
if (!mod2sparse_at_end(e) && mod2sparse_col(e)>i)
{ fprintf(stderr,
"mod2sparse_tunnel_sub: Matrix is not lower-triangular\n");
exit(1);
}
}
/* Solve system by tunnel substitution. */
for (i = 0; i<K; i++)
{
ii = rows ? rows[i] : i;
/* Look at bits in this row, forming inner product with partial
solution, and seeing if the diagonal is 1. */
d = 0;
b = 0;
for (e = mod2sparse_first_in_row(L,ii);
!mod2sparse_at_end(e);
e = mod2sparse_next_in_row(e))
{
j = mod2sparse_col(e);
if (j==i)
{ d = 1;
}
else
{ b ^= y[j];
}
}
/* Check for no solution if the diagonal isn't 1. */
if (!d && b!=x[ii])
{ return 0;
}
/* Set bit of solution, zero if arbitrary. */
y[i] = b^x[ii];
}
return 1;
}
void make_ldpc
( int seed, /* Random number seed */
make_method method, /* How to make it */
distrib *d, /* Distribution list specified */
int no4cycle /* Eliminate cycles of length four? */
)
{
mod2entry *e, *f, *g, *h;
int added, uneven, elim4, all_even, n_full, left;
int i, j, k, t, z, cb_N;
int *part, *u;
rand_seed(10*seed+1);
H = mod2sparse_allocate(M,N);
part = column_partition(d,N);
/* Create the initial version of the parity check matrix. */
switch (method)
{
case Evencol:
{
z = 0;
left = part[z];
for (j = 0; j<N; j++)
{ while (left==0)
{ z += 1;
if (z>distrib_size(d))
{ abort();
}
left = part[z];
}
for (k = 0; k<distrib_num(d,z); k++)
{ do
{ i = rand_int(M);
} while (mod2sparse_find(H,i,j));
mod2sparse_insert(H,i,j);
}
left -= 1;
}
break;
}
case Evenboth:
{
cb_N = 0;
for (z = 0; z<distrib_size(d); z++)
{ cb_N += distrib_num(d,z) * part[z];
}
u = chk_alloc (cb_N, sizeof *u);
for (k = cb_N-1; k>=0; k--)
{ u[k] = k%M;
}
uneven = 0;
t = 0;
z = 0;
left = part[z];
for (j = 0; j<N; j++)
{
while (left==0)
{ z += 1;
if (z>distrib_size(d))
{ abort();
}
left = part[z];
}
for (k = 0; k<distrib_num(d,z); k++)
{
for (i = t; i<cb_N && mod2sparse_find(H,u[i],j); i++) ;
if (i==cb_N)
{ uneven += 1;
do
{ i = rand_int(M);
} while (mod2sparse_find(H,i,j));
mod2sparse_insert(H,i,j);
}
else
{ do
{ i = t + rand_int(cb_N-t);
} while (mod2sparse_find(H,u[i],j));
mod2sparse_insert(H,u[i],j);
u[i] = u[t];
t += 1;
}
}
left -= 1;
}
if (uneven>0)
{ fprintf(stderr,"Had to place %d checks in rows unevenly\n",uneven);
}
break;
}
default: abort();
}
/* Add extra bits to avoid rows with less than two checks. */
added = 0;
for (i = 0; i<M; i++)
{ e = mod2sparse_first_in_row(H,i);
if (mod2sparse_at_end(e))
{ j = rand_int(N);
e = mod2sparse_insert(H,i,j);
added += 1;
}
e = mod2sparse_first_in_row(H,i);
if (mod2sparse_at_end(mod2sparse_next_in_row(e)) && N>1)
{ do
{ j = rand_int(N);
} while (j==mod2sparse_col(e));
mod2sparse_insert(H,i,j);
added += 1;
}
}
if (added>0)
{ fprintf(stderr,
"Added %d extra bit-checks to make row counts at least two\n",
added);
}
/* Add extra bits to try to avoid problems with even column counts. */
n_full = 0;
all_even = 1;
for (z = 0; z<distrib_size(d); z++)
{ if (distrib_num(d,z)==M)
{ n_full += part[z];
}
if (distrib_num(d,z)%2==1)
{ all_even = 0;
}
}
if (all_even && N-n_full>1 && added<2)
{ int a;
for (a = 0; added+a<2; a++)
{ do
{ i = rand_int(M);
j = rand_int(N);
} while (mod2sparse_find(H,i,j));
mod2sparse_insert(H,i,j);
}
fprintf(stderr,
"Added %d extra bit-checks to try to avoid problems from even column counts\n",
a);
}
/* Eliminate cycles of length four, if asked, and if possible. */
if (no4cycle)
{
elim4 = 0;
for (t = 0; t<10; t++)
{ k = 0;
for (j = 0; j<N; j++)
{ for (e = mod2sparse_first_in_col(H,j);
!mod2sparse_at_end(e);
e = mod2sparse_next_in_col(e))
{ for (f = mod2sparse_first_in_row(H,mod2sparse_row(e));
!mod2sparse_at_end(f);
f = mod2sparse_next_in_row(f))
{ if (f==e) continue;
for (g = mod2sparse_first_in_col(H,mod2sparse_col(f));
!mod2sparse_at_end(g);
g = mod2sparse_next_in_col(g))
{ if (g==f) continue;
for (h = mod2sparse_first_in_row(H,mod2sparse_row(g));
!mod2sparse_at_end(h);
h = mod2sparse_next_in_row(h))
{ if (mod2sparse_col(h)==j)
{ do
{ i = rand_int(M);
} while (mod2sparse_find(H,i,j));
mod2sparse_delete(H,e);
mod2sparse_insert(H,i,j);
elim4 += 1;
k += 1;
goto nextj;
}
}
}
}
}
nextj: ;
}
if (k==0) break;
}
if (elim4>0)
{ fprintf(stderr,
"Eliminated %d cycles of length four by moving checks within column\n",
elim4);
}
if (t==10)
{ fprintf(stderr,
"Couldn't eliminate all cycles of length four in 10 passes\n");
}
}
}
mod2sparse* CreatePchkMatrix ( int nbRows, int nbCols, make_method makeMethod, int leftDegree, int seed, bool no4cycle, SessionType type, int verbosity )
{
mod2entry *e;
#if 0
mod2entry *f, *g, *h; /* using by no4cycle mode */
int elim4;
#endif
int added, uneven;
int i, j, k, t;
int *u;
mod2sparse *pchkMatrix = NULL;
int skipCols = 0; // avoid warning
int nbDataCols = 0; // avoid warning
if (type != TypeLDGM && type != TypeSTAIRS && type != TypeTRIANGLE) {
fprintf(stderr, "unsupported code type (%d)\n", type);
return NULL;
}
skipCols = nbRows;
nbDataCols = nbCols-skipCols;
// Check for some problems.
if (leftDegree>nbRows)
{
fprintf(stderr, "ERROR, Number of checks per bit (%d) is greater than total checks (%d)\n", leftDegree, nbRows);
return NULL;
}
#if 0
if (leftDegree==nbRows && nbCols>1 && no4cycle)
{
fprintf(stderr, "ERROR, Can't eliminate cycles of length four with this many checks per bit\n");
return NULL;
}
#endif
if (no4cycle) {
fprintf(stderr, "ERROR: no4cycle mode is no longer supported!\n");
exit(-1);
}
ldpc_srand(seed);
pchkMatrix = mod2sparse_allocate(nbRows, nbCols);
/* Create the initial version of the parity check matrix. */
switch (makeMethod)
{
case Evencol:
for(j=skipCols; j<nbCols; j++)
{
for(k=0; k<leftDegree; k++)
{
do
{
i = ldpc_rand(nbRows);
}
while (mod2sparse_find(pchkMatrix,i,j));
mod2sparse_insert(pchkMatrix,i,j);
}
}
break;
case Evenboth:
u = (int*)chk_alloc (leftDegree*nbDataCols, sizeof *u);
/* initialize a list of possible choices to guarantee a homogeneous "1" distribution */
for(k = leftDegree*nbDataCols-1; k>=0; k--)
{
u[k] = k%nbRows;
}
uneven = 0;
t = 0; /* left limit within the list of possible choices, u[] */
for(j = skipCols; j<nbCols; j++) /* for each source symbol column */
{
for(k = 0; k<leftDegree; k++) /* add left_degree "1s" */
{
/* check that valid available choices remain */
for(i = t; i<leftDegree*nbDataCols && mod2sparse_find(pchkMatrix,u[i],j); i++) ;
if(i < leftDegree*nbDataCols)
{
/* choose one index within the list of possible choices */
do {
i = t + ldpc_rand(leftDegree*nbDataCols-t);
} while (mod2sparse_find(pchkMatrix,u[i],j));
mod2sparse_insert(pchkMatrix,u[i],j);
/* replace with u[t] which has never been chosen */
u[i] = u[t];
t++;
}
else
{
/* no choice left, choose one randomly */
uneven += 1;
do {
i = ldpc_rand(nbRows);
} while (mod2sparse_find(pchkMatrix,i,j));
mod2sparse_insert(pchkMatrix,i,j);
}
}
}
if(uneven > 0 && verbosity >= 1)
{
fprintf(stderr,"Had to place %d checks in rows unevenly\n",uneven);
}
free(u); /* VR: added */
break;
default: abort();
}
/* Add extra bits to avoid rows with less than two checks. */
added = 0;
for(i = 0; i<nbRows; i++)
{
e = mod2sparse_first_in_row(pchkMatrix,i);
if(mod2sparse_at_end(e))
{
j = (ldpc_rand(nbDataCols))+skipCols;
e = mod2sparse_insert(pchkMatrix,i,j);
added ++;
}
e = mod2sparse_first_in_row(pchkMatrix,i);
if(mod2sparse_at_end(mod2sparse_next_in_row(e)) && nbDataCols>1)
{
do
{
j = (ldpc_rand(nbDataCols))+skipCols;
} while (j==mod2sparse_col(e));
mod2sparse_insert(pchkMatrix,i,j);
added ++;
}
}
if(added > 0 && verbosity >= 1)
{
fprintf(stderr, "Added %d extra bit-checks to make row counts at least two\n", added);
}
/* Add extra bits to try to avoid problems with even column counts. */
if(leftDegree%2==0 && leftDegree<nbRows && nbDataCols>1 && added<2)
{
int a;
for(a = 0; added+a<2; a++)
{
do
{
i = ldpc_rand(nbRows);
j = (ldpc_rand(nbDataCols))+skipCols;
} while (mod2sparse_find(pchkMatrix,i,j));
mod2sparse_insert(pchkMatrix,i,j);
}
if (verbosity >= 1) {
fprintf(stderr, "Added %d extra bit-checks to try to avoid problems from even column counts\n", a);
}
}
#if 0
/* Eliminate cycles of length four, if asked, and if possible. */
if(no4cycle)
{
elim4 = 0;
for(t = 0; t<10; t++)
{
k = 0;
for(j = 0; j<nbCols; j++)
{
for( e=mod2sparse_first_in_col(pchkMatrix,j); !mod2sparse_at_end(e); e=mod2sparse_next_in_col(e) )
{
for( f=mod2sparse_first_in_row(pchkMatrix,mod2sparse_row(e)); !mod2sparse_at_end(f); f=mod2sparse_next_in_row(f) )
{
if(f==e) continue;
for(g=mod2sparse_first_in_col(pchkMatrix,mod2sparse_col(f)); !mod2sparse_at_end(g); g=mod2sparse_next_in_col(g) )
{
if(g==f) continue;
for( h=mod2sparse_first_in_row(pchkMatrix,mod2sparse_row(g)); !mod2sparse_at_end(h); h = mod2sparse_next_in_row(h) )
{
if(mod2sparse_col(h)==j)
{
do
{
i = ldpc_rand(nbRows);
}
while (mod2sparse_find(pchkMatrix,i,j));
mod2sparse_delete(pchkMatrix,e);
mod2sparse_insert(pchkMatrix,i,j);
elim4 += 1;
k += 1;
goto nextj;
}
}
}
}
}
nextj: ;
}
if(k==0) break;
}
if(elim4>0)
{
fprintf(stderr, "Eliminated %d cycles of length four by moving checks within column\n", elim4);
}
if(t==10)
{
fprintf(stderr, "Couldn't eliminate all cycles of length four in 10 passes\n");
}
}
#endif
switch (type) {
case TypeLDGM:
for (i = 0; i < nbRows; i++) {
/* identity */
mod2sparse_insert(pchkMatrix, i, i);
}
break;
case TypeSTAIRS:
mod2sparse_insert(pchkMatrix, 0, 0); /* 1st row */
for (i = 1; i < nbRows; i++) { /* for all other rows */
/* identity */
mod2sparse_insert(pchkMatrix, i, i);
/* staircase */
mod2sparse_insert(pchkMatrix, i, i-1);
}
break;
case TypeTRIANGLE:
mod2sparse_insert(pchkMatrix, 0, 0); /* 1st row */
for (i = 1; i < nbRows; i++) { /* for all other rows */
/* identity */
mod2sparse_insert(pchkMatrix, i, i);
/* staircase */
mod2sparse_insert(pchkMatrix, i, i-1);
/* triangle */
j = i-1;
for (int l = 0; l < j; l++) { /* limit the # of "1s" added */
j = ldpc_rand(j);
mod2sparse_insert(pchkMatrix, i, j);
}
}
break;
}
return pchkMatrix;
}
int main
( int argc,
char **argv
)
{
char *alist_file, *pchk_file;
FILE *af, *pf;
int mxrw, mxcw;
int *rw, *cw;
int i, j, k;
mod2entry *e;
int trans;
int nozeros;
int last;
trans = 0;
nozeros = 0;
for (;;)
{
if (argc>1 && strcmp(argv[1],"-t")==0)
{ trans = 1;
argc -= 1;
argv += 1;
}
else if (argc>1 && strcmp(argv[1],"-z")==0)
{ nozeros = 1;
argc -= 1;
argv += 1;
}
else
{ break;
}
}
if (argc!=3)
{ usage();
}
pchk_file = argv[1];
alist_file = argv[2];
read_pchk(pchk_file);
if (trans)
{ mod2sparse *HT;
HT = H;
H = mod2sparse_allocate(N,M);
mod2sparse_transpose(HT,H);
M = mod2sparse_rows(H);
N = mod2sparse_cols(H);
}
af = open_file_std(alist_file,"wb");
if (af==NULL)
{ fprintf(stderr,"Can't create alist file: %s\n",alist_file);
exit(1);
}
fprintf(af,"%d %d\n",M,N);
rw = (int *) chk_alloc (M, sizeof *rw);
mxrw = 0;
for (i = 0; i<M; i++)
{ rw[i] = mod2sparse_count_row(H,i);
if (rw[i]>mxrw)
{ mxrw = rw[i];
}
}
cw = (int *) chk_alloc (N, sizeof *cw);
mxcw = 0;
for (j = 0; j<N; j++)
{ cw[j] = mod2sparse_count_col(H,j);
if (cw[j]>mxcw)
{ mxcw = cw[j];
}
}
fprintf(af,"%d %d\n",mxrw,mxcw);
for (i = 0; i<M; i++)
{ fprintf(af,"%d%c",rw[i],i==M-1?'\n':' ');
}
for (j = 0; j<N; j++)
{ fprintf(af,"%d%c",cw[j],j==N-1?'\n':' ');
}
for (i = 0; i<M; i++)
{ e = mod2sparse_first_in_row(H,i);
last = 0;
for (k = 0; !last; k++)
{ last = nozeros ? k==rw[i]-1 : k==mxrw-1;
fprintf (af, "%d%c", mod2sparse_at_end(e)?0:mod2sparse_col(e)+1,
last?'\n':' ');
if (!mod2sparse_at_end(e))
{ e = mod2sparse_next_in_row(e);
}
}
}
for (j = 0; j<N; j++)
{ e = mod2sparse_first_in_col(H,j);
last = 0;
for (k = 0; !last; k++)
{ last = nozeros ? k==cw[j]-1 : k==mxcw-1;
fprintf (af, "%d%c", mod2sparse_at_end(e)?0:mod2sparse_row(e)+1,
last?'\n':' ');
if (!mod2sparse_at_end(e))
{ e = mod2sparse_next_in_col(e);
}
}
}
if (ferror(af) || fclose(af)!=0)
{ fprintf(stderr,"Error writing to alist file %s\n",alist_file);
exit(1);
}
return 0;
}