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std.compress.zstandard: cleanup ReverseBitReader

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This commit is contained in:
dweiller 2023-01-23 12:47:46 +11:00
parent c819e58c20
commit cbfaa876d4
1 changed files with 42 additions and 49 deletions
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91
lib/std/compress/zstandard/decompress.zig
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@ -68,8 +68,7 @@ const DecodeState = struct {
fse_tables_undefined: bool,
literal_stream_reader: ReverseBitReader(ReversedByteReader.Reader),
literal_stream_bytes: ReversedByteReader,
literal_stream_reader: ReverseBitReader,
literal_stream_index: usize,
huffman_tree: ?Literals.HuffmanTree,
@ -288,9 +287,7 @@ const DecodeState = struct {
fn initLiteralStream(self: *DecodeState, bytes: []const u8) !void {
log.debug("initing literal stream: {}", .{std.fmt.fmtSliceHexUpper(bytes)});
self.literal_stream_bytes = reversedByteReader(bytes);
self.literal_stream_reader = reverseBitReader(self.literal_stream_bytes.reader());
while (0 == try self.literal_stream_reader.readBitsNoEof(u1, 1)) {}
try self.literal_stream_reader.init(bytes);
}
fn decodeLiteralsSlice(self: *DecodeState, dest: []u8, literals: Literals, len: usize) !void {
@ -532,7 +529,6 @@ pub fn decodeZStandardFrameAlloc(allocator: std.mem.Allocator, src: []const u8,
.literal_written_count = 0,
.literal_stream_reader = undefined,
.literal_stream_bytes = undefined,
.literal_stream_index = undefined,
.huffman_tree = null,
};
@ -591,7 +587,6 @@ pub fn decodeFrameBlocks(dest: []u8, src: []const u8, consumed_count: *usize, ha
.literal_written_count = 0,
.literal_stream_reader = undefined,
.literal_stream_bytes = undefined,
.literal_stream_index = undefined,
.huffman_tree = null,
};
@ -725,10 +720,9 @@ pub fn decodeBlock(
var bytes_written: usize = 0;
if (sequences_header.sequence_count > 0) {
const bit_stream_bytes = src[bytes_read..block_size];
var reverse_byte_reader = reversedByteReader(bit_stream_bytes);
var bit_stream = reverseBitReader(reverse_byte_reader.reader());
var bit_stream: ReverseBitReader = undefined;
try bit_stream.init(bit_stream_bytes);
while (0 == try bit_stream.readBitsNoEof(u1, 1)) {}
try decode_state.readInitialState(&bit_stream);
var i: usize = 0;
@ -791,10 +785,9 @@ pub fn decodeBlockRingBuffer(
var bytes_written: usize = 0;
if (sequences_header.sequence_count > 0) {
const bit_stream_bytes = src[bytes_read..block_size];
var reverse_byte_reader = reversedByteReader(bit_stream_bytes);
var bit_stream = reverseBitReader(reverse_byte_reader.reader());
var bit_stream: ReverseBitReader = undefined;
try bit_stream.init(bit_stream_bytes);
while (0 == try bit_stream.readBitsNoEof(u1, 1)) {}
try decode_state.readInitialState(&bit_stream);
var i: usize = 0;
@ -1028,9 +1021,8 @@ fn decodeHuffmanTree(src: []const u8, consumed_count: *usize) !Literals.HuffmanT
const accuracy_log = std.math.log2_int_ceil(usize, table_size);
var huff_data = src[1 + counting_reader.bytes_read .. compressed_size + 1];
var huff_data_bytes = reversedByteReader(huff_data);
var huff_bits = reverseBitReader(huff_data_bytes.reader());
while (0 == try huff_bits.readBitsNoEof(u1, 1)) {}
var huff_bits: ReverseBitReader = undefined;
try huff_bits.init(huff_data);
dumpFseTable("huffman", entries[0..table_size]);
@ -1415,48 +1407,49 @@ const ReversedByteReader = struct {
const Reader = std.io.Reader(*ReversedByteReader, error{}, readFn);
fn init(bytes: []const u8) ReversedByteReader {
return .{
.bytes = bytes,
.remaining_bytes = bytes.len,
};
}
fn reader(self: *ReversedByteReader) Reader {
return .{ .context = self };
}
fn readFn(ctx: *ReversedByteReader, buffer: []u8) !usize {
if (ctx.remaining_bytes == 0) return 0;
const byte_index = ctx.remaining_bytes - 1;
buffer[0] = ctx.bytes[byte_index];
// buffer[0] = @bitReverse(ctx.bytes[byte_index]);
ctx.remaining_bytes = byte_index;
return 1;
}
};
fn readFn(ctx: *ReversedByteReader, buffer: []u8) !usize {
if (ctx.remaining_bytes == 0) return 0;
const byte_index = ctx.remaining_bytes - 1;
buffer[0] = ctx.bytes[byte_index];
// buffer[0] = @bitReverse(ctx.bytes[byte_index]);
ctx.remaining_bytes = byte_index;
return 1;
}
const ReverseBitReader = struct {
byte_reader: ReversedByteReader,
bit_reader: std.io.BitReader(.Big, ReversedByteReader.Reader),
fn reversedByteReader(bytes: []const u8) ReversedByteReader {
return ReversedByteReader{
.remaining_bytes = bytes.len,
.bytes = bytes,
};
}
fn init(self: *ReverseBitReader, bytes: []const u8) !void {
self.byte_reader = ReversedByteReader.init(bytes);
self.bit_reader = std.io.bitReader(.Big, self.byte_reader.reader());
while (0 == self.readBitsNoEof(u1, 1) catch return error.BitStreamHasNoStartBit) {}
}
fn ReverseBitReader(comptime Reader: type) type {
return struct {
underlying: std.io.BitReader(.Big, Reader),
fn readBitsNoEof(self: *@This(), comptime U: type, num_bits: usize) !U {
return self.bit_reader.readBitsNoEof(U, num_bits);
}
fn readBitsNoEof(self: *@This(), comptime U: type, num_bits: usize) !U {
return self.underlying.readBitsNoEof(U, num_bits);
}
fn readBits(self: *@This(), comptime U: type, num_bits: usize, out_bits: *usize) !U {
return try self.bit_reader.readBits(U, num_bits, out_bits);
}
fn readBits(self: *@This(), comptime U: type, num_bits: usize, out_bits: *usize) !U {
return try self.underlying.readBits(U, num_bits, out_bits);
}
fn alignToByte(self: *@This()) void {
self.underlying.alignToByte();
}
};
}
fn reverseBitReader(reader: anytype) ReverseBitReader(@TypeOf(reader)) {
return .{ .underlying = std.io.bitReader(.Big, reader) };
}
fn alignToByte(self: *@This()) void {
self.bit_reader.alignToByte();
}
};
fn BitReader(comptime Reader: type) type {
return struct {