Overview
Comment: | The decompressor now tries to fill in the whole output buffer in a single call. |
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Downloads: | Tarball | ZIP archive | SQL archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
1f73d90f65ec364f62075e5c5a5b0666 |
User & Date: | spaskalev on 2014-12-21 23:24:04 |
Other Links: | manifest | tags |
Context
2014-12-22
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16:41 | Integrate the decompressor2 branch into trunk now that it is faster. check-in: 6d10a1d28f user: spaskalev tags: trunk | |
2014-12-21
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23:24 | The decompressor now tries to fill in the whole output buffer in a single call. check-in: 1f73d90f65 user: spaskalev tags: trunk | |
22:52 | Removed TODOs, renamed readCount->rc, wrapped->reader check-in: 630530df49 user: spaskalev tags: trunk | |
Changes
Modified src/0dev.org/predictor/predictor.go from [090d2f3fd4] to [9dfe9174f8].
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// and decompresses data according to the predictor algorithm func Decompressor(reader io.Reader) io.Reader { var ctx context ctx.input = make([]byte, 0, 8) return decompressor(func(output []byte) (int, error) { var ( err error flags byte rc, total int ) // Sanity check for space to read into if len(output) == 0 { return 0, nil } ................................................................................ // Check whether we still have leftover data in the buffer :) if rc < len(ctx.input) { ctx.input = ctx.input[:copy(ctx.input, ctx.input[rc:])] } return rc, nil } // Read the flags rc, err = reader.Read(ctx.input[:1]) if rc == 0 || (err != nil && err != io.EOF) { return rc, err } ctx.input = ctx.input[:8] flags = ctx.input[0] var i uint = 0 for ; i < 8; i++ { if flags&(1<<i) > 0 { // Guess was right ctx.input[i] = ctx.table[ctx.hash] } else { rc, err = reader.Read(ctx.input[i:(i + 1)]) if err == io.EOF { break } if err != nil { return rc, err } if rc == 0 { // treat as EoF break } ctx.table[ctx.hash] = ctx.input[i] } ctx.hash = (ctx.hash << 4) ^ uint16(ctx.input[i]) } rc = copy(output, ctx.input[:i]) total += rc // Place any remaining bytes in the buffer if uint(rc) < i { ctx.input = ctx.input[:copy(ctx.input, ctx.input[rc:i])] } else { ctx.input = ctx.input[:0] } return total, err }) } |
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// and decompresses data according to the predictor algorithm func Decompressor(reader io.Reader) io.Reader { var ctx context ctx.input = make([]byte, 0, 8) return decompressor(func(output []byte) (int, error) { var ( err error flags byte i, rc, total int ) // Sanity check for space to read into if len(output) == 0 { return 0, nil } ................................................................................ // Check whether we still have leftover data in the buffer :) if rc < len(ctx.input) { ctx.input = ctx.input[:copy(ctx.input, ctx.input[rc:])] } return rc, nil } loop: // Read the flags rc, err = reader.Read(ctx.input[:1]) if err != nil && err != io.EOF { return 0, err } if rc == 0 { return total, err } ctx.input = ctx.input[:8] flags = ctx.input[0] for i = 0; i < 8; i++ { if flags&(1<<uint(i)) > 0 { // Guess was right ctx.input[i] = ctx.table[ctx.hash] } else { rc, err = reader.Read(ctx.input[i:(i + 1)]) if err == io.EOF { break } if err != nil { return total, err } if rc == 0 { // treat as EoF break } ctx.table[ctx.hash] = ctx.input[i] } ctx.hash = (ctx.hash << 4) ^ uint16(ctx.input[i]) } rc = copy(output, ctx.input[:i]) total += rc // Place any remaining bytes in the buffer if rc < i { ctx.input = ctx.input[:copy(ctx.input, ctx.input[rc:i])] } else { // Clear the buffer ctx.input = ctx.input[:0] // Advance the output buffer ... output = output[i:] // ... and decompress the next block if there is any space left if len(output) > 0 && err != io.EOF { goto loop } } return total, err }) } |
Modified src/0dev.org/predictor/predictor_test.go from [dd11cf49de] to [0dde784b22].
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// Diff the result against the initial input delta := diff.Diff(diff.D{len(input), len(decompressed), func(i, j int) bool { return input[i] == decompressed[j] }}) // Return a well-formated error if any differences are found if len(delta.Added) > 0 || len(delta.Removed) > 0 { return fmt.Errorf("Unexpected decompressed output %v\ninput: %#x\ntrace: %#x\noutput: %#x\n", delta, input, trace, decompressed) } // All is good :) return nil } |
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// Diff the result against the initial input delta := diff.Diff(diff.D{len(input), len(decompressed), func(i, j int) bool { return input[i] == decompressed[j] }}) // Return a well-formated error if any differences are found if len(delta.Added) > 0 || len(delta.Removed) > 0 { return fmt.Errorf("Unexpected decompressed output %v\ninput: (%d) %#x\ntrace: (%d) %#x\noutput: (%d) %#x\n", delta, len(input), input, len(trace), trace, len(decompressed), decompressed) } // All is good :) return nil } |