Base64 encoder

main.zig

const std = @import("std");
const gpa = std.heap.page_allocator;

const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

pub fn main() !void {
    const text = "AAA";

    var base64Length = (text.len / 3) * 4;
    if ((text.len % 3) > 0) {
        base64Length += 4;
    }

    var base64 = try gpa.alloc(u8, base64Length);
    defer gpa.free(base64);

    var textIndex: usize = 0;
    var base64Index: usize = 0;
    while (textIndex < text.len) {
        var b: u8 = text[textIndex] >> 2;
        base64[base64Index] = chars[b];
        base64Index += 1;

        b = text[textIndex] & 0b11;
        b <<= 4;
        textIndex += 1;
        if (textIndex >= text.len) {
            base64[base64Index] = chars[b];
            base64[base64Index + 1] = '=';
            base64[base64Index + 2] = '=';
            break;
        }

        b += text[textIndex] >> 4;
        base64[base64Index] = chars[b];
        base64Index += 1;

        b = text[textIndex] & 0b1111;
        b <<= 2;
        textIndex += 1;
        if (textIndex >= text.len) {
            base64[base64Index] = chars[b];
            base64[base64Index + 1] = '=';
            break;
        }

        b += text[textIndex] >> 6;
        base64[base64Index] = chars[b];
        base64Index += 1;

        b = text[textIndex] & 0b111111;
        base64[base64Index] = chars[b];
        base64Index += 1;

        textIndex += 1;
    }

    std.debug.print("{s}\n", .{base64});
}