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| <h3 class="section">2.2 <code>a64l</code>, <code>l64a</code>—convert between radix-64 ASCII string and long</h3> |
| |
| <p><a name="index-a64l-2"></a><a name="index-l64a-3"></a><strong>Synopsis</strong> |
| <pre class="example"> #include <stdlib.h> |
| long a64l(const char *<var>input</var>); |
| char *l64a(long <var>input</var>); |
| |
| </pre> |
| <p><strong>Description</strong><br> |
| Conversion is performed between long and radix-64 characters. The |
| <code>l64a</code> routine transforms up to 32 bits of input value starting from |
| least significant bits to the most significant bits. The input value |
| is split up into a maximum of 5 groups of 6 bits and possibly one |
| group of 2 bits (bits 31 and 30). |
| |
| <p>Each group of 6 bits forms a value from 0–63 which is translated into |
| a character as follows: |
| |
| <ul> |
| <li>0 = '.' |
| <li>1 = '/' |
| <li>2–11 = '0' to '9' |
| <li>12–37 = 'A' to 'Z' |
| <li>38–63 = 'a' to 'z' |
| </ul> |
| |
| <p>When the remaining bits are zero or all bits have been translated, a |
| null terminator is appended to the string. An input value of 0 |
| results in the empty string. |
| |
| <p>The <code>a64l</code> function performs the reverse translation. Each |
| character is used to generate a 6-bit value for up to 30 bits and then |
| a 2-bit value to complete a 32-bit result. The null terminator means |
| that the remaining digits are 0. An empty input string or NULL string |
| results in 0L. An invalid string results in undefined behavior. If |
| the size of a long is greater than 32 bits, the result is sign-extended. |
| |
| <p><br> |
| <strong>Returns</strong><br> |
| <code>l64a</code> returns a null-terminated string of 0 to 6 characters. |
| <code>a64l</code> returns the 32-bit translated value from the input character string. |
| |
| <p><br> |
| <strong>Portability</strong><br> |
| <code>l64a</code> and <code>a64l</code> are non-ANSI and are defined by the Single Unix Specification. |
| |
| <p>Supporting OS subroutines required: None. |
| |
| <p><br> |
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