libzahl

big integer library
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zbits.3 (707B)

      1 .TH ZBITS 3 libzahl
      2 .SH NAME
      3 zbits - Count used bits in a big integer
      4 .SH SYNOPSIS
      5 .nf
      6 #include <zahl.h>
      7 
      8 size_t zbits(z_t \fIa\fP);
      9 .fi
     10 .SH DESCRIPTION
     11 .B zbits
     12 calculates the bit-size of
     13 .IR a .
     14 If
     15 .I a
     16 is zero the bit-size is 1.
     17 .SH RETURN VALUE
     18 .B zbits
     19 returns the number of bits requires
     20 to represent
     21 .I a
     22 \(em 1 plus the floored binary logarithm of the
     23 absolute value of
     24 .I a
     25 \(em or 1 if
     26 .I a
     27 is zero.
     28 .SH RATIONALE
     29 .B zbits
     30 returns 1 rather than 0 if
     31 .B a
     32 is zero, this is to avoid off-by-one errors
     33 and it is the number of digits requires to
     34 write the number in binary. You will see this
     35 in corresponding functions in other libraries.
     36 .SH SEE ALSO
     37 .BR zlsb (3),
     38 .BR zzero (3),
     39 .BR zstr_length (3)