mirror of
https://github.com/ziglang/zig.git
synced 2025-12-07 06:43:07 +00:00
490f067de8
Replaces the inflate API from `inflateStream(reader: anytype, window_slice: []u8)` to `decompressor(allocator: mem.Allocator, reader: anytype, dictionary: ?[]const u8)` and `compressor(allocator: mem.Allocator, writer: anytype, options: CompressorOptions)`
105 lines
3.8 KiB
Zig
105 lines
3.8 KiB
Zig
// 2 bits: type, can be 0 (literal), 1 (EOF), 2 (Match) or 3 (Unused).
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// 8 bits: xlength (length - MIN_MATCH_LENGTH).
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// 22 bits: xoffset (offset - MIN_OFFSET_SIZE), or literal.
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const length_shift = 22;
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const offset_mask = (1 << length_shift) - 1; // 4_194_303
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const literal_type = 0 << 30; // 0
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pub const match_type = 1 << 30; // 1_073_741_824
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// The length code for length X (MIN_MATCH_LENGTH <= X <= MAX_MATCH_LENGTH)
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// is length_codes[length - MIN_MATCH_LENGTH]
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var length_codes = [_]u32{
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0, 1, 2, 3, 4, 5, 6, 7, 8, 8,
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9, 9, 10, 10, 11, 11, 12, 12, 12, 12,
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13, 13, 13, 13, 14, 14, 14, 14, 15, 15,
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15, 15, 16, 16, 16, 16, 16, 16, 16, 16,
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17, 17, 17, 17, 17, 17, 17, 17, 18, 18,
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18, 18, 18, 18, 18, 18, 19, 19, 19, 19,
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19, 19, 19, 19, 20, 20, 20, 20, 20, 20,
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20, 20, 20, 20, 20, 20, 20, 20, 20, 20,
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21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
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21, 21, 21, 21, 21, 21, 22, 22, 22, 22,
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22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
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22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
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23, 23, 23, 23, 23, 23, 23, 23, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
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25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
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25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
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25, 25, 25, 25, 25, 25, 25, 25, 25, 25,
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25, 25, 26, 26, 26, 26, 26, 26, 26, 26,
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26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
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26, 26, 26, 26, 26, 26, 26, 26, 26, 26,
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26, 26, 26, 26, 27, 27, 27, 27, 27, 27,
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27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
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27, 27, 27, 27, 27, 27, 27, 27, 27, 27,
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27, 27, 27, 27, 27, 28,
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};
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var offset_codes = [_]u32{
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0, 1, 2, 3, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7,
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8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9,
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10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
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11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11,
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12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
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12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
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13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
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13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15,
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};
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pub const Token = u32;
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// Convert a literal into a literal token.
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pub fn literalToken(lit: u32) Token {
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return literal_type + lit;
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}
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// Convert a < xlength, xoffset > pair into a match token.
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pub fn matchToken(xlength: u32, xoffset: u32) Token {
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return match_type + (xlength << length_shift) + xoffset;
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}
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// Returns the literal of a literal token
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pub fn literal(t: Token) u32 {
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return @intCast(u32, t - literal_type);
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}
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// Returns the extra offset of a match token
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pub fn offset(t: Token) u32 {
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return @intCast(u32, t) & offset_mask;
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}
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pub fn length(t: Token) u32 {
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return @intCast(u32, (t - match_type) >> length_shift);
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}
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pub fn lengthCode(len: u32) u32 {
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return length_codes[len];
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}
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// Returns the offset code corresponding to a specific offset
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pub fn offsetCode(off: u32) u32 {
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if (off < @intCast(u32, offset_codes.len)) {
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return offset_codes[off];
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}
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if (off >> 7 < @intCast(u32, offset_codes.len)) {
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return offset_codes[off >> 7] + 14;
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}
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return offset_codes[off >> 14] + 28;
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}
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test {
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const std = @import("std");
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const expect = std.testing.expect;
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try expect(matchToken(555, 555) == 3_401_581_099);
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}
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