Started work on stateful decompression

src/decomp/zstd.zig

@@ -0,0 +1,119 @@
+const std = @import("std");
+const builtin = @import("builtin");
+
+const c = @import("c.zig").c;
+const DCtx = c.ZSTD_DCtx;
+
+const Self = @This();
+
+alloc: std.mem.Allocator,
+ctx: std.AutoHashMap(std.Thread.Id, DCtx),
+
+pub fn init(alloc: std.mem.Allocator) !Self {
+    return .{
+        .alloc = alloc,
+        .ctx = .init(alloc),
+    };
+}
+pub fn deinit(self: Self) void {
+    var iter = self.ctx.keyIterator();
+    while (iter.next()) |key| {
+        _ = c.ZSTD_freeDCtx(self.ctx.getPtr(key));
+    }
+    self.ctx.deinit(self.alloc);
+}
+
+pub fn decompress(self: *Self, in: []u8, out: []u8) ZstdError!usize {
+    const ctx = try self.getOrCreate();
+    const res = c.ZSTD_decompressDCtx(ctx, out.ptr, out.len, in.ptr, in.len);
+    try checkError(res);
+    return res;
+}
+inline fn getOrCreate(self: *Self) ZstdError!*DCtx {
+    const res = try self.ctx.getOrPut(std.Thread.getCurrentId());
+    if (res.found_existing) {
+        try checkError(c.ZSTD_DCtx_reset(res.value_ptr, c.ZSTD_reset_session_only));
+        return res.value_ptr;
+    }
+    res.value_ptr.* = c.ZSTD_createDCtx() orelse return ZstdError.OutOfMemory;
+    return res.value_ptr;
+}
+
+fn stateless(alloc: std.mem.Allocator, in: []u8, out: []u8) anyerror!usize {
+    _ = alloc;
+    const res = c.ZSTD_decompress(out.ptr, out.len, in.ptr, in.len);
+    try checkError(res);
+    return res;
+}
+
+inline fn checkError(res: usize) !void {
+    if (res == 0) return;
+    if (c.ZSTD_isError(res) == 0) return;
+    return switch (c.ZSTD_getErrorCode(res)) {
+        c.ZSTD_error_prefix_unknown => ZstdError.PrefixUnknown,
+        c.ZSTD_error_version_unsupported => ZstdError.VersionUnsupported,
+        c.ZSTD_error_frameParameter_unsupported => ZstdError.FrameParameterUnsupported,
+        c.ZSTD_error_frameParameter_windowTooLarge => ZstdError.FrameParameterWindowTooLarge,
+        c.ZSTD_error_corruption_detected => ZstdError.CorruptionDetected,
+        c.ZSTD_error_checksum_wrong => ZstdError.ChecksumWrong,
+        c.ZSTD_error_literals_headerWrong => ZstdError.LiteralsHeaderWrong,
+        c.ZSTD_error_dictionary_corrupted => ZstdError.DictionaryCorrupted,
+        c.ZSTD_error_dictionary_wrong => ZstdError.DictionaryWrong,
+        c.ZSTD_error_dictionaryCreation_failed => ZstdError.DictionaryCreationFailed,
+        c.ZSTD_error_parameter_unsupported => ZstdError.ParameterUnsupported,
+        c.ZSTD_error_parameter_combination_unsupported => ZstdError.ParameterCombinationUnsupported,
+        c.ZSTD_error_parameter_outOfBound => ZstdError.ParameterOutOfBound,
+        c.ZSTD_error_tableLog_tooLarge => ZstdError.TableLogTooLarge,
+        c.ZSTD_error_maxSymbolValue_tooLarge => ZstdError.MaxSymbolValueTooLarge,
+        c.ZSTD_error_maxSymbolValue_tooSmall => ZstdError.MaxSymbolValueTooSmall,
+        c.ZSTD_error_stabilityCondition_notRespected => ZstdError.StabilityConditionNotRespected,
+        c.ZSTD_error_stage_wrong => ZstdError.StageWrong,
+        c.ZSTD_error_init_missing => ZstdError.InitMissing,
+        c.ZSTD_error_memory_allocation => ZstdError.MemoryAllocation,
+        c.ZSTD_error_workSpace_tooSmall => ZstdError.WorkSpaceTooSmall,
+        c.ZSTD_error_dstSize_tooSmall => ZstdError.DstSizeTooSmall,
+        c.ZSTD_error_srcSize_wrong => ZstdError.SrcSizeWrong,
+        c.ZSTD_error_dstBuffer_null => ZstdError.DstBufferNull,
+        c.ZSTD_error_noForwardProgress_destFull => ZstdError.NoForwardProgressDestFull,
+        c.ZSTD_error_noForwardProgress_inputEmpty => ZstdError.NoForwardProgressInputEmpty,
+        else => ZstdError.Generic,
+    };
+}
+pub const ZstdError = error{
+    OutOfMemory,
+    Generic,
+    PrefixUnknown,
+    VersionUnsupported,
+    FrameParameterUnsupported,
+    FrameParameterWindowTooLarge,
+    CorruptionDetected,
+    ChecksumWrong,
+    LiteralsHeaderWrong,
+    DictionaryCorrupted,
+    DictionaryWrong,
+    DictionaryCreationFailed,
+    ParameterUnsupported,
+    ParameterCombinationUnsupported,
+    ParameterOutOfBound,
+    TableLogTooLarge,
+    MaxSymbolValueTooLarge,
+    MaxSymbolValueTooSmall,
+    CannotProduceUncompressedBlock,
+    StabilityConditionNotRespected,
+    StageWrong,
+    InitMissing,
+    MemoryAllocation,
+    WorkSpaceTooSmall,
+    DstSizeTooSmall,
+    SrcSizeWrong,
+    DstBufferNull,
+    NoForwardProgressDestFull,
+    NoForwardProgressInputEmpty,
+    FrameIndexTooLarge,
+    SeekableIo,
+    DstBufferWrong,
+    SrcBufferWrong,
+    SequenceProducerFailed,
+    ExternalSequencesInvalid,
+    MaxCode,
+};