Game Boy Advance “Hello World” Using Zig(github.com)

    const std = @import("std");
    const Allocator = std.mem.Allocator;
    const ArrayList = std.ArrayList;
    
    // This is all ripped from Zig's C allocator, with adaptations to point to
    // SQLite's allocator instead.
    pub const allocator = &allocator_state;
    var allocator_state = Allocator{
        .reallocFn = realloc,
        .shrinkFn = shrink,
    };
    
    fn realloc(self: *Allocator,
               old_mem: []u8,
               old_align: u29,
               new_size: usize,
               new_align: u29) ![]u8 {
        std.debug.assert(new_align <= @alignOf(c_longdouble));
        const old_ptr =
            if (old_mem.len == 0) null else @ptrCast(*c_void, old_mem.ptr);
        const buf = sqlite3_realloc64(old_ptr, @intCast(u64, new_size))
            orelse return error.OutOfMemory;
        return @ptrCast([*]u8, buf)[0..new_size];
    }
    
    fn shrink(self: *Allocator,
              old_mem: []u8,
              old_align: u29,
              new_size: usize,
              new_align: u29) []u8 {
        const old_ptr = @ptrCast(*c_void, old_mem.ptr);
        const buf = sqlite3_realloc64(old_ptr, @intCast(u64, new_size))
            orelse return old_mem[0..new_size];
        return @ptrCast([*]u8, buf)[0..new_size];
    }

    pub fn open(name: []const u8) !Database {
        // "allocator" here being the const-defined one above
        var cstrName = try std.cstr.addNullByte(allocator, name);
        defer allocator.free(cstrName);
        var db: Database = undefined;
        var rc = sqlite3_open(cstrName.ptr, &db);
    
        if (rc == SQLITE_OK) {
            return db;
        } else {
            _ = sqlite3_close(db);
            return errorCode(rc);
        }
    }