zbits.3 - libzahl - big integer library | |
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zbits.3 (707B) | |
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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) |