Add core:encoding/uuid

core/encoding/uuid/reading.odin

@@ -0,0 +1,97 @@
+package uuid
+
+/*
+Convert a string to a UUID.
+
+Inputs:
+- str: A string in the 8-4-4-4-12 format.
+
+Returns:
+- id: The converted identifier, or `nil` if there is an error.
+- error: A description of the error, or `nil` if successful.
+*/
+read :: proc "contextless" (str: string) -> (id: Identifier, error: Read_Error) #no_bounds_check {
+	// Only exact-length strings are acceptable.
+	if len(str) != EXPECTED_LENGTH {
+		return {}, .Invalid_Length
+	}
+
+	// Check ahead to see if the separators are in the right places.
+	if str[8] != '-' || str[13] != '-' || str[18] != '-' || str[23] != '-' {
+		return {}, .Invalid_Separator
+	}
+
+	read_nibble :: proc "contextless" (nibble: u8) -> u8 {
+		switch nibble {
+		case '0' ..= '9':
+			return nibble - '0'
+		case 'A' ..= 'F':
+			return nibble - 'A' + 10
+		case 'a' ..= 'f':
+			return nibble - 'a' + 10
+		case:
+			// Return an error value.
+			return 0xFF
+		}
+	}
+
+	index := 0
+	octet_index := 0
+
+	CHUNKS :: [5]int{8, 4, 4, 4, 12}
+
+	for chunk in CHUNKS {
+		for i := index; i < index + chunk; i += 2 {
+			high := read_nibble(str[i])
+			low := read_nibble(str[i + 1])
+
+			if high | low > 0xF {
+				return {}, .Invalid_Hexadecimal
+			}
+
+			id.bytes[octet_index] = low | high << 4
+			octet_index += 1
+		}
+
+		index += chunk + 1
+	}
+
+	return
+}
+
+/*
+Get the version of a UUID.
+
+Inputs:
+- id: The identifier.
+
+Returns:
+- number: The version number.
+*/
+version :: proc "contextless" (id: Identifier) -> (number: int) #no_bounds_check {
+	return cast(int)(id.bytes[VERSION_BYTE_INDEX] & 0xF0 >> 4)
+}
+
+/*
+Get the variant of a UUID.
+
+Inputs:
+- id: The identifier.
+
+Returns:
+- variant: The variant type.
+*/
+variant :: proc "contextless" (id: Identifier) -> (variant: Variant_Type) #no_bounds_check {
+	switch {
+	case id.bytes[VARIANT_BYTE_INDEX] & 0x80 == 0:
+		return .Reserved_Apollo_NCS
+	case id.bytes[VARIANT_BYTE_INDEX] & 0xC0 == 0x80:
+		return .RFC_4122
+	case id.bytes[VARIANT_BYTE_INDEX] & 0xE0 == 0xC0:
+		return .Reserved_Microsoft_COM
+	case id.bytes[VARIANT_BYTE_INDEX] & 0xF0 == 0xE0:
+		return .Reserved_Future
+	case:
+		return .Unknown
+	}
+}