Commit 1b43551190

Andrew Kelley <andrew@ziglang.org>
2025-07-28 01:16:56
std.Io: remove BitWriter
1 parent 824c157
Changed files (4)
lib/std/compress/flate/HuffmanEncoder.zig
@@ -421,19 +421,6 @@ test "generate a Huffman code for the 30 possible relative distances (LZ77 dista
     }
 }
 
-test "fixedLiteralEncoder codes" {
-    var al = std.ArrayList(u8).init(testing.allocator);
-    defer al.deinit();
-    var bw = std.Io.bitWriter(.little, al.writer());
-
-    var codes: [max_num_frequencies]Code = undefined;
-    const f = fixedLiteralEncoder(&codes);
-    for (f.codes) |c| {
-        try bw.writeBits(c.code, c.len);
-    }
-    try testing.expectEqualSlices(u8, &fixed_codes, al.items);
-}
-
 pub const fixed_codes = [_]u8{
     0b00001100, 0b10001100, 0b01001100, 0b11001100, 0b00101100, 0b10101100, 0b01101100, 0b11101100,
     0b00011100, 0b10011100, 0b01011100, 0b11011100, 0b00111100, 0b10111100, 0b01111100, 0b11111100,
lib/std/Io/bit_writer.zig
@@ -1,179 +0,0 @@
-const std = @import("../std.zig");
-
-//General note on endianess:
-//Big endian is packed starting in the most significant part of the byte and subsequent
-// bytes contain less significant bits. Thus we write out bits from the high end
-// of our input first.
-//Little endian is packed starting in the least significant part of the byte and
-// subsequent bytes contain more significant bits. Thus we write out bits from
-// the low end of our input first.
-//Regardless of endianess, within any given byte the bits are always in most
-// to least significant order.
-//Also regardless of endianess, the buffer always aligns bits to the low end
-// of the byte.
-
-/// Creates a bit writer which allows for writing bits to an underlying standard writer
-pub fn BitWriter(comptime endian: std.builtin.Endian, comptime Writer: type) type {
-    return struct {
-        writer: Writer,
-        bits: u8 = 0,
-        count: u4 = 0,
-
-        const low_bit_mask = [9]u8{
-            0b00000000,
-            0b00000001,
-            0b00000011,
-            0b00000111,
-            0b00001111,
-            0b00011111,
-            0b00111111,
-            0b01111111,
-            0b11111111,
-        };
-
-        /// Write the specified number of bits to the writer from the least significant bits of
-        ///  the specified value. Bits will only be written to the writer when there
-        ///  are enough to fill a byte.
-        pub fn writeBits(self: *@This(), value: anytype, num: u16) !void {
-            const T = @TypeOf(value);
-            const UT = std.meta.Int(.unsigned, @bitSizeOf(T));
-            const U = if (@bitSizeOf(T) < 8) u8 else UT; //<u8 is a pain to work with
-
-            var in: U = @as(UT, @bitCast(value));
-            var in_count: u16 = num;
-
-            if (self.count > 0) {
-                //if we can't fill the buffer, add what we have
-                const bits_free = 8 - self.count;
-                if (num < bits_free) {
-                    self.addBits(@truncate(in), @intCast(num));
-                    return;
-                }
-
-                //finish filling the buffer and flush it
-                if (num == bits_free) {
-                    self.addBits(@truncate(in), @intCast(num));
-                    return self.flushBits();
-                }
-
-                switch (endian) {
-                    .big => {
-                        const bits = in >> @intCast(in_count - bits_free);
-                        self.addBits(@truncate(bits), bits_free);
-                    },
-                    .little => {
-                        self.addBits(@truncate(in), bits_free);
-                        in >>= @intCast(bits_free);
-                    },
-                }
-                in_count -= bits_free;
-                try self.flushBits();
-            }
-
-            //write full bytes while we can
-            const full_bytes_left = in_count / 8;
-            for (0..full_bytes_left) |_| {
-                switch (endian) {
-                    .big => {
-                        const bits = in >> @intCast(in_count - 8);
-                        try self.writer.writeByte(@truncate(bits));
-                    },
-                    .little => {
-                        try self.writer.writeByte(@truncate(in));
-                        if (U == u8) in = 0 else in >>= 8;
-                    },
-                }
-                in_count -= 8;
-            }
-
-            //save the remaining bits in the buffer
-            self.addBits(@truncate(in), @intCast(in_count));
-        }
-
-        //convenience funciton for adding bits to the buffer
-        //in the appropriate position based on endianess
-        fn addBits(self: *@This(), bits: u8, num: u4) void {
-            if (num == 8) self.bits = bits else switch (endian) {
-                .big => {
-                    self.bits <<= @intCast(num);
-                    self.bits |= bits & low_bit_mask[num];
-                },
-                .little => {
-                    const pos = bits << @intCast(self.count);
-                    self.bits |= pos;
-                },
-            }
-            self.count += num;
-        }
-
-        /// Flush any remaining bits to the writer, filling
-        /// unused bits with 0s.
-        pub fn flushBits(self: *@This()) !void {
-            if (self.count == 0) return;
-            if (endian == .big) self.bits <<= @intCast(8 - self.count);
-            try self.writer.writeByte(self.bits);
-            self.bits = 0;
-            self.count = 0;
-        }
-    };
-}
-
-pub fn bitWriter(comptime endian: std.builtin.Endian, writer: anytype) BitWriter(endian, @TypeOf(writer)) {
-    return .{ .writer = writer };
-}
-
-///////////////////////////////
-
-test "api coverage" {
-    var mem_be = [_]u8{0} ** 2;
-    var mem_le = [_]u8{0} ** 2;
-
-    var mem_out_be = std.io.fixedBufferStream(&mem_be);
-    var bit_stream_be = bitWriter(.big, mem_out_be.writer());
-
-    const testing = std.testing;
-
-    try bit_stream_be.writeBits(@as(u2, 1), 1);
-    try bit_stream_be.writeBits(@as(u5, 2), 2);
-    try bit_stream_be.writeBits(@as(u128, 3), 3);
-    try bit_stream_be.writeBits(@as(u8, 4), 4);
-    try bit_stream_be.writeBits(@as(u9, 5), 5);
-    try bit_stream_be.writeBits(@as(u1, 1), 1);
-
-    try testing.expect(mem_be[0] == 0b11001101 and mem_be[1] == 0b00001011);
-
-    mem_out_be.pos = 0;
-
-    try bit_stream_be.writeBits(@as(u15, 0b110011010000101), 15);
-    try bit_stream_be.flushBits();
-    try testing.expect(mem_be[0] == 0b11001101 and mem_be[1] == 0b00001010);
-
-    mem_out_be.pos = 0;
-    try bit_stream_be.writeBits(@as(u32, 0b110011010000101), 16);
-    try testing.expect(mem_be[0] == 0b01100110 and mem_be[1] == 0b10000101);
-
-    try bit_stream_be.writeBits(@as(u0, 0), 0);
-
-    var mem_out_le = std.io.fixedBufferStream(&mem_le);
-    var bit_stream_le = bitWriter(.little, mem_out_le.writer());
-
-    try bit_stream_le.writeBits(@as(u2, 1), 1);
-    try bit_stream_le.writeBits(@as(u5, 2), 2);
-    try bit_stream_le.writeBits(@as(u128, 3), 3);
-    try bit_stream_le.writeBits(@as(u8, 4), 4);
-    try bit_stream_le.writeBits(@as(u9, 5), 5);
-    try bit_stream_le.writeBits(@as(u1, 1), 1);
-
-    try testing.expect(mem_le[0] == 0b00011101 and mem_le[1] == 0b10010101);
-
-    mem_out_le.pos = 0;
-    try bit_stream_le.writeBits(@as(u15, 0b110011010000101), 15);
-    try bit_stream_le.flushBits();
-    try testing.expect(mem_le[0] == 0b10000101 and mem_le[1] == 0b01100110);
-
-    mem_out_le.pos = 0;
-    try bit_stream_le.writeBits(@as(u32, 0b1100110100001011), 16);
-    try testing.expect(mem_le[0] == 0b00001011 and mem_le[1] == 0b11001101);
-
-    try bit_stream_le.writeBits(@as(u0, 0), 0);
-}
lib/std/Io/test.zig
@@ -57,51 +57,6 @@ test "write a file, read it, then delete it" {
     try tmp.dir.deleteFile(tmp_file_name);
 }
 
-test "BitStreams with File Stream" {
-    var tmp = tmpDir(.{});
-    defer tmp.cleanup();
-
-    const tmp_file_name = "temp_test_file.txt";
-    {
-        var file = try tmp.dir.createFile(tmp_file_name, .{});
-        defer file.close();
-
-        var bit_stream = io.bitWriter(native_endian, file.deprecatedWriter());
-
-        try bit_stream.writeBits(@as(u2, 1), 1);
-        try bit_stream.writeBits(@as(u5, 2), 2);
-        try bit_stream.writeBits(@as(u128, 3), 3);
-        try bit_stream.writeBits(@as(u8, 4), 4);
-        try bit_stream.writeBits(@as(u9, 5), 5);
-        try bit_stream.writeBits(@as(u1, 1), 1);
-        try bit_stream.flushBits();
-    }
-    {
-        var file = try tmp.dir.openFile(tmp_file_name, .{});
-        defer file.close();
-
-        var bit_stream = io.bitReader(native_endian, file.deprecatedReader());
-
-        var out_bits: u16 = undefined;
-
-        try expect(1 == try bit_stream.readBits(u2, 1, &out_bits));
-        try expect(out_bits == 1);
-        try expect(2 == try bit_stream.readBits(u5, 2, &out_bits));
-        try expect(out_bits == 2);
-        try expect(3 == try bit_stream.readBits(u128, 3, &out_bits));
-        try expect(out_bits == 3);
-        try expect(4 == try bit_stream.readBits(u8, 4, &out_bits));
-        try expect(out_bits == 4);
-        try expect(5 == try bit_stream.readBits(u9, 5, &out_bits));
-        try expect(out_bits == 5);
-        try expect(1 == try bit_stream.readBits(u1, 1, &out_bits));
-        try expect(out_bits == 1);
-
-        try expectError(error.EndOfStream, bit_stream.readBitsNoEof(u1, 1));
-    }
-    try tmp.dir.deleteFile(tmp_file_name);
-}
-
 test "File seek ops" {
     var tmp = tmpDir(.{});
     defer tmp.cleanup();
lib/std/Io.zig
@@ -470,9 +470,6 @@ pub const countingReader = @import("Io/counting_reader.zig").countingReader;
 pub const BitReader = @import("Io/bit_reader.zig").BitReader;
 pub const bitReader = @import("Io/bit_reader.zig").bitReader;
 
-pub const BitWriter = @import("Io/bit_writer.zig").BitWriter;
-pub const bitWriter = @import("Io/bit_writer.zig").bitWriter;
-
 pub const tty = @import("Io/tty.zig");
 
 /// Deprecated in favor of `Writer.Discarding`.
@@ -951,7 +948,6 @@ test {
     _ = Reader.Limited;
     _ = Writer;
     _ = BitReader;
-    _ = BitWriter;
     _ = BufferedReader;
     _ = BufferedWriter;
     _ = CountingWriter;