Complete project1

base64/src/base64.zig

@@ -0,0 +1,138 @@
+const std = @import("std");
+
+pub const Base64 = struct {
+    _table: *const [64]u8,
+
+    pub fn init() Base64 {
+        const upper  = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+        const lower  = "abcdefghijklmnopqrstuvwxyz";
+        const numsym = "0123456789+/";
+
+        return Base64 {
+            ._table = upper ++ lower ++ numsym,
+        };
+    }
+
+    pub fn encode(self: Base64, allocator: std.mem.Allocator, input: [] const u8) ![]u8 {
+        if (input.len == 0) {
+            return "";
+        }
+
+        const n_out   = try _calc_encode_length(input);
+        const out     = try allocator.alloc(u8, n_out);
+        var buf       = [3]u8{0, 0, 0};
+        var count: u8 = 0;
+        var iout: u64 = 0;
+
+        for (input, 0..) |_, i| {
+            buf[count] = input[i];
+            count += 1;
+            if (count == 3) {
+                out[iout] = self._char_at(buf[0] >> 2);
+                out[iout + 1] = self._char_at(((buf[0] & 0x03) << 4) + (buf[1] >> 4));
+                out[iout + 2] = self._char_at(((buf[1] & 0x0f) << 2) + (buf[2] >> 6));
+                out[iout + 3] = self._char_at(buf[2] & 0x3f);
+
+                iout += 4;
+                count = 0;
+            }
+        }
+
+        if (count == 1)  {
+            out[iout] = self._char_at(buf[0] >> 2);
+            out[iout + 1] = self._char_at((buf[0] & 0x03) << 4);
+            out[iout + 2] = '=';
+            out[iout + 3] = '=';
+        }
+
+        if (count == 2) {
+            out[iout] = self._char_at(buf[0] >> 2);
+            out[iout + 1] = self._char_at(((buf[0] & 0x03) << 4) + (buf[1] >> 4));
+            out[iout + 2] = self._char_at((buf[1] & 0x0f) << 2);
+            out[iout + 3] = '=';
+
+            iout += 4;
+        }
+
+        return out;
+    }
+
+    pub fn decode(self: Base64, allocator: std.mem.Allocator, input: [] const u8) ![]u8 {
+        if (input.len == 0) {
+            return "";
+        }
+
+        const n_out   = try _calc_decode_length(input);
+        const out     = try allocator.alloc(u8, n_out);
+        var buf       = [4]u8{0, 0, 0, 0};
+        var count: u8 = 0;
+        var iout: u64 = 0;
+
+        for (input, 0..) |_, i| {
+            buf[count] = self._char_index(input[i]);
+            count += 1;
+            if (count == 4) {
+                out[iout] = (buf[0] << 2) + (buf[1] >> 4);
+                if (buf[2] != 64) {
+                    out[iout + 1] = (buf[1] << 4) + (buf[2] >> 2);
+                }
+                if (buf[3] != 64) {
+                    out[iout + 2] = (buf[2] << 6) + buf[3];
+                }
+
+                iout += 3;
+                count = 0;
+            }
+        }
+
+        return out;
+    }
+
+    fn _char_at(self: Base64, index: usize) u8 {
+        return self._table[index];
+    }
+
+    fn _char_index(self: Base64, char: u8) u8 {
+        if (char == '=') {
+            return 64;
+        }
+
+        var index: u8 = 0;
+        for (0..63) |i| {
+            if (self._char_at(i) == char) {
+                break;
+            }
+            index += 1;
+        }
+
+        return index;
+    }
+
+    fn _calc_encode_length(input: [] const u8) !usize {
+        if (input.len < 3) {
+            return 4;
+        }
+
+        const n_groups = try std.math.divCeil(usize, input.len, 3);
+
+        return n_groups * 4;
+    }
+
+    fn _calc_decode_length(input: [] const u8) !usize {
+        if (input.len < 4) {
+            return 3;
+        }
+
+        const n_groups = try std.math.divFloor(usize, input.len, 4);
+
+        var groups: usize = n_groups * 3;
+        var i: usize = input.len - 1;
+        while (i > 0) : (i -= 1) {
+            if (input[i] == '=') {
+                groups -= 1;
+            }
+        }
+
+        return groups;
+    }
+};

base64/src/main.zig

@@ -0,0 +1,19 @@
+const std = @import("std");
+const Base64 = @import("base64.zig").Base64;
+
+pub fn main() !void {
+    const stdout = std.io.getStdOut().writer();
+    var memory_buffer: [1000]u8 = undefined;
+    var fba = std.heap.FixedBufferAllocator.init(
+        &memory_buffer
+    );
+    const allocator = fba.allocator();
+
+    const text = "Testing some more stuff";
+    const etext = "VGVzdGluZyBzb21lIG1vcmUgc3R1ZmY=";
+    const base64 = Base64.init();
+    const encoded_text = try base64.encode(allocator, text);
+    const decoded_text = try base64.decode(allocator, etext);
+    try stdout.print("Encoded text: {s}\n", .{encoded_text});
+    try stdout.print("Decoded text: {s}\n", .{decoded_text});
+}