Added Base32 + official test vectors from the RFC

core/encoding/base32/base32.odin

@@ -0,0 +1,180 @@
+package base32
+
+// @note(zh): Encoding utility for Base32
+// A secondary param can be used to supply a custom alphabet to
+// @link(encode) and a matching decoding table to @link(decode). 
+// If none is supplied it just uses the standard Base32 alphabet.
+// Incase your specific version does not use padding, you may
+// truncate it from the encoded output.
+
+ENC_TABLE := [32]byte {
+    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
+    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 
+    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 
+    'Y', 'Z', '2', '3', '4', '5', '6', '7'
+};
+
+PADDING :: '=';
+
+DEC_TABLE := [?]u8 {
+	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  
+     0,  0, 26, 27, 28, 29, 30, 31,  0,  0,  0,  0,  0,  0,  0,  0,
+	 0,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 
+    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,  0,  0,  0,  0,  0,
+	 0,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 
+    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,  0,  0,  0,  0,  0,
+	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+	 0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0
+};
+
+encode :: proc(data: []byte, ENC_TBL := ENC_TABLE, allocator := context.allocator) -> string {
+    out_length := (len(data) + 4) / 5 * 8;
+    out := make([]byte, out_length);
+    _encode(out, data);
+    return string(out);
+}
+
+@private
+_encode :: inline proc "contextless"(out, data: []byte, ENC_TBL := ENC_TABLE, allocator := context.allocator) {
+    out := out;
+    data := data;
+
+    for len(data) > 0 {
+        carry: byte;
+		switch len(data) {
+            case:
+                out[7] = ENC_TABLE[data[4] & 0x1f];
+                carry = data[4] >> 5;
+                fallthrough;
+            case 4:
+                out[6] = ENC_TABLE[carry | (data[3] << 3) & 0x1f];
+                out[5] = ENC_TABLE[(data[3] >> 2) & 0x1f];
+                carry = data[3] >> 7;
+                fallthrough;
+            case 3:
+                out[4] = ENC_TABLE[carry | (data[2] << 1) & 0x1f];
+                carry = (data[2] >> 4) & 0x1f;
+                fallthrough;
+            case 2:
+                out[3] = ENC_TABLE[carry | (data[1] << 4) & 0x1f];
+                out[2] = ENC_TABLE[(data[1] >> 1) & 0x1f];
+                carry = (data[1] >> 6) & 0x1f;
+                fallthrough;
+            case 1:
+                out[1] = ENC_TABLE[carry | (data[0] << 2) & 0x1f];
+                out[0] = ENC_TABLE[data[0] >> 3];
+		}
+
+        if len(data) < 5 {
+			out[7] = byte(PADDING);
+			if len(data) < 4 {
+				out[6] = byte(PADDING);
+				out[5] = byte(PADDING);
+				if len(data) < 3 {
+					out[4] = byte(PADDING);
+					if len(data) < 2 {
+						out[3] = byte(PADDING);
+						out[2] = byte(PADDING);
+					}
+				}
+			}
+			break;
+		}
+        data = data[5:];
+        out = out[8:];
+    }
+}
+
+decode :: proc(data: string, DEC_TBL := DEC_TABLE, allocator := context.allocator) -> []byte #no_bounds_check{
+    if len(data) == 0 do return []byte{};
+
+    outi := 0;
+	olen := len(data);
+    data := data;
+
+    out := make([]byte, len(data) / 8 * 5, allocator);
+    end := false;
+    for len(data) > 0 && !end {
+		dbuf : [8]byte;
+		dlen := 8;
+
+		for j := 0; j < 8; {
+			if len(data) == 0 {
+				dlen, end = j, true;
+				break;
+			}
+			input := data[0];
+			data = data[1:];
+			if input == byte(PADDING) && j >= 2 && len(data) < 8 {
+                assert(!(len(data) + j < 8 - 1), "Corrupted input");
+				for k := 0; k < 8-1-j; k +=1 do assert(len(data) < k || data[k] == byte(PADDING), "Corrupted input");
+				dlen, end = j, true;
+                assert(dlen != 1 && dlen != 3 && dlen != 6, "Corrupted input");
+				break;
+			}
+			dbuf[j] = DEC_TABLE[input];
+            assert(dbuf[j] != 0xff, "Corrupted input");
+			j += 1;
+		}
+
+		switch dlen {
+            case 8:
+                out[outi + 4] = dbuf[6] << 5 | dbuf[7];
+                fallthrough;
+            case 7:
+                out[outi + 3] = dbuf[4] << 7 | dbuf[5] << 2 | dbuf[6] >> 3;
+                fallthrough;
+            case 5:
+                out[outi + 2] = dbuf[3] << 4 | dbuf[4] >> 1;
+                fallthrough;
+            case 4:
+                out[outi + 1] = dbuf[1] << 6 | dbuf[2] << 1 | dbuf[3] >> 4;
+                fallthrough;
+            case 2:
+                out[outi + 0] = dbuf[0] << 3 | dbuf[1] >> 2;
+		}
+		outi += 5;
+	}
+    return out;
+}
+
+// @note(zh): Test inputs. Taken from RFC4648
+/*
+import "core:fmt"
+main :: proc() {
+    Test :: struct {
+        plain: string,
+        encoded: string,
+    };
+
+    test_vectors := [?]Test {
+        Test{"", ""},
+        Test{"f", "MY======"},
+        Test{"fo", "MZXQ===="},
+        Test{"foo", "MZXW6==="},
+        Test{"foob", "MZXW6YQ="},
+        Test{"fooba", "MZXW6YTB"},
+        Test{"foobar", "MZXW6YTBOI======"},
+    };
+
+    // Encode test
+    for v in test_vectors {
+        enc := encode(([]byte)(v.plain));
+        fmt.printf("encode(\"%s\") => \"%s\" \t| want: \"%s\"\n", v.plain, enc, v.encoded);
+        delete(enc);
+    }
+
+    // Decode test
+    for v in test_vectors {
+        dec := decode(v.encoded);
+        fmt.printf("decode(\"%s\") => \"%s\" \t| want: \"%s\"\n", v.encoded, string(dec), v.plain);
+        delete(dec);
+    }
+}
+*/