51 lines
1.2 KiB
Vala
51 lines
1.2 KiB
Vala
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namespace Xmpp.Util {
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// Parse a number from a hexadecimal representation.
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//
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// Skips any whitespace at the start of the string, parses as many valid
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// characters as hexadecimal digits as possible (possibly zero) and returns
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// them as an integer value.
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//
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// ```
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// // 0x0
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// print("0x%lx\n", from_hex(""));
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//
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// // 0x123abc
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// print("0x%lx\n", from_hex("123abc"));
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//
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// // 0x0
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// print("0x%lx\n", from_hex("0x123abc"));
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//
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// // 0xa
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// print("0x%lx\n", from_hex("A quick brown fox jumps over the lazy dog."));
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//
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// // 0xfeed
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// print("0x%lx\n", from_hex(" FEED ME "));
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// ```
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public long from_hex(string numeral) {
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long result = 0;
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bool skipping_whitespace = true;
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foreach (uint8 byte in numeral.data) {
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char c = (char)byte;
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if (skipping_whitespace && c.isspace()) {
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continue;
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}
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skipping_whitespace = false;
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int digit;
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if ('0' <= c && c <= '9') {
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digit = c - '0';
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} else if ('A' <= c && c <= 'F') {
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digit = c - 'A' + 10;
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} else if ('a' <= c && c <= 'f') {
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digit = c - 'a' + 10;
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} else {
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break;
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}
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result = (result << 4) | digit;
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}
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return result;
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}
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}
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