Complete base64 project

base64/base64.odin

@@ -0,0 +1,142 @@
+package main
+
+import "core:math"
+import "core:strings"
+
+@(private="file")
+alphabet := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+encode :: proc(s: string) -> string {
+  if len(s) == 0 do return "";
+
+  n_out := calc_encode_length(s);
+
+  bytes := make([]u8, n_out);
+  defer delete(bytes);
+
+  buf : [3]u8 = {};
+  count : u8 = 0;
+  iout : u64 = 0;
+
+  for i in 0..<len(s) {
+    buf[count] = s[i];
+    count += 1;
+    if count == 3 {
+      bytes[iout] = char_at(buf[0] >> 2);
+      bytes[iout + 1] = char_at(((buf[0] & 0x03) << 4) + (buf[1] >> 4));
+      bytes[iout + 2] = char_at(((buf[1] & 0x0f) << 2) + (buf[2] >> 6));
+      bytes[iout + 3] = char_at(buf[2] & 0x3f);
+
+      iout += 4;
+      count = 0;
+    }
+  }
+
+  if count == 1 {
+    bytes[iout] = char_at(buf[0] >> 2);
+    bytes[iout + 1] = char_at((buf[0] & 0x03) << 4);
+    bytes[iout + 2] = '=';
+    bytes[iout + 3] = '=';
+  }
+
+  if count == 2 {
+    bytes[iout] = char_at(buf[0] >> 2);
+    bytes[iout + 1] = char_at(((buf[0] & 0x03) << 4) + (buf[1] >> 4));
+    bytes[iout + 2] = char_at((buf[1] & 0x0f) << 2);
+    bytes[iout + 3] = '=';
+
+    iout += 4;
+  }
+
+  output, err := strings.clone_from_bytes(bytes[:]);
+  if err != nil {
+    return "";
+  }
+
+  return output;
+}
+
+decode :: proc(s: string) -> string {
+  if len(s) == 0 do return "";
+
+  n_out := calc_decode_length(s);
+
+  bytes := make([]u8, n_out);
+  defer delete(bytes);
+
+  buf : [4]u8 = {};
+  count : u8 = 0;
+  iout : u64 = 0;
+
+  for i in 0..<len(s) {
+    buf[count] = char_index(s[i]);
+    count += 1;
+    if count == 4 {
+      bytes[iout] = (buf[0] << 2) + (buf[1] >> 4);
+      if buf[2] != 64 {
+        bytes[iout + 1] = (buf[1] << 4) + (buf[2] >> 2);
+      }
+      if buf[3] != 64 {
+        bytes[iout + 2] = (buf[2] << 6) + buf[3];
+      }
+
+      iout += 3;
+      count = 0;
+    }
+  }
+
+  output, err := strings.clone_from_bytes(bytes[:]);
+  if err != nil {
+    return "";
+  }
+
+  return output;
+}
+
+@(private="file")
+char_at :: proc(index: u8) -> u8 {
+  return alphabet[index];
+}
+
+@(private="file")
+char_index :: proc(char: u8) -> u8 {
+  if char == '=' {
+    return 64;
+  }
+
+  index : u8 = 0;
+  for c in alphabet {
+    if c == rune(char) do break;
+    index += 1;
+  }
+
+  return index;
+}
+
+@(private="file")
+calc_encode_length :: proc(s: string) -> u64 {
+  if len(s) < 3 {
+    return 4;
+  }
+
+  groups := u64(math.ceil_f32(f32(len(s)) / 3.0));
+
+  return groups * 4;
+}
+
+@(private="file")
+calc_decode_length :: proc(s: string) -> u64 {
+  if len(s) < 4 {
+    return 3;
+  }
+
+  n_groups := u64(math.floor_f32(f32(len(s)) / 4.0));
+  groups := n_groups * 3;
+  #reverse for char in s {
+    if char == '=' {
+      groups -= 1;
+    }
+  }
+
+  return groups;
+}

base64/main.odin

@@ -0,0 +1,17 @@
+package main
+
+import "core:fmt"
+
+main :: proc() {
+  text :: "Testing some more stuff";
+  etext :: "VGVzdGluZyBzb21lIG1vcmUgc3R1ZmY=";
+
+  encoded_text := encode(text);
+  defer delete(encoded_text);
+
+  decoded_text := decode(etext);
+  defer delete(decoded_text);
+
+  fmt.println("Encoded text:", encoded_text);
+  fmt.println("Decoded text:", decoded_text);
+}