1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/Chunk.cpp	Sun Sep 20 15:14:12 2009 -0700
     1.3 @@ -0,0 +1,135 @@
     1.4 +/*
     1.5 + *  Chunk.cpp
     1.6 + *  Ottoman
     1.7 + *
     1.8 + *  Created by Jens Alfke on 8/27/09.
     1.9 + *  Copyright 2009 Jens Alfke. All rights reserved.
    1.10 + *  BSD-Licensed: See the file "LICENSE.txt" for details.
    1.11 + */
    1.12 +
    1.13 +#include "Chunk.h"
    1.14 +#include <assert.h>
    1.15 +#include <errno.h>
    1.16 +#include <stddef.h>
    1.17 +
    1.18 +namespace Mooseyard {
    1.19 +    
    1.20 +    uint16_t Chunk::type() const {
    1.21 +        return _keyLength == 0xFFFF ?(uint16_t)_type :KeyValueChunk::kChunkType;
    1.22 +    }
    1.23 +    
    1.24 +    const KeyValueChunk* Chunk::asKeyValue() const {
    1.25 +        return _keyLength == 0xFFFF ?NULL :(const KeyValueChunk*)this;
    1.26 +    }
    1.27 +
    1.28 +    size_t Chunk::writeMultiple (File *file, uint16_t type,
    1.29 +                                 Blob blobs[], int count)  throw(File::Error) {
    1.30 +        assert(type != KeyValueChunk::kChunkType);
    1.31 +        Blob nuBlobs[count+1];
    1.32 +        uint32_t size = sizeof(Chunk);
    1.33 +        for (int i=0; i<count; i++) {
    1.34 +            nuBlobs[i+1] = blobs[i];
    1.35 +            size += blobs[i].length;
    1.36 +        }
    1.37 +        Chunk chunk(size, type);
    1.38 +        nuBlobs[0] = Blob(&chunk, sizeof(chunk));
    1.39 +        return file->writeMultiple(nuBlobs, count+1);
    1.40 +    }
    1.41 +    
    1.42 +    size_t Chunk::writePadding (File *file) {
    1.43 +        int padding = file->position() & 0x03;
    1.44 +        if (padding == 0)
    1.45 +            return 0;
    1.46 +        else {
    1.47 +            padding = 4 - padding;
    1.48 +            uint32_t zero = 0;
    1.49 +            Blob pad(&zero, padding);
    1.50 +            return writeMultiple(file, kChunkTypePadding, &pad, 1);
    1.51 +        }
    1.52 +    }
    1.53 +    
    1.54 +    
    1.55 +    
    1.56 +    void KeyValueChunk::validate() const  throw(File::Error) {
    1.57 +        if (_keyLength >= 0xFFFFU)
    1.58 +            throw File::Error(ERANGE, "Invalid key length (0xFFFF)");
    1.59 +        if (valuePtr() > end())
    1.60 +            throw File::Error(ERANGE, "Bad KeyValueChunk (key-length too large to fit)");
    1.61 +    }
    1.62 +    
    1.63 +    Blob KeyValueChunk::key() const {
    1.64 +        return Blob(&_keyLength +1, _keyLength);  // KeyValueChunk doesn't have _type
    1.65 +    }
    1.66 +    
    1.67 +    const char* KeyValueChunk::valuePtr() const {
    1.68 +        size_t vptr = (size_t) key().end();
    1.69 +        vptr = (vptr+3) & ~3;     // 4-byte align
    1.70 +        return (const char*)vptr;
    1.71 +    }
    1.72 +    
    1.73 +    Blob KeyValueChunk::value() const {
    1.74 +        const char *vp = valuePtr();
    1.75 +        return Blob(vp, (const char*)end()-vp);
    1.76 +    }
    1.77 +    
    1.78 +    bool KeyValueChunk::hasKey (Blob key) const {
    1.79 +        return key.length==_keyLength 
    1.80 +            && memcmp(key.bytes, &_keyLength +1, key.length)==0;
    1.81 +    }
    1.82 +    
    1.83 +    size_t KeyValueChunk::write (File* file, FilePosition pos, Blob key, Blob value)  throw(File::Error) {
    1.84 +        if (key.length >= 0xFFFFU)
    1.85 +            throw File::Error(ERANGE, "Key too long (>=64k)");
    1.86 +        uint16_t keyLength = key.length;
    1.87 +        uint32_t size = sizeof(uint32_t) + sizeof(uint16_t) + keyLength;
    1.88 +        size_t pad = (pos + size) & 0x3;
    1.89 +        if (pad)
    1.90 +            pad = 4-pad;
    1.91 +        uint32_t zeros = 0;
    1.92 +        size += pad + value.length;
    1.93 +        
    1.94 +        Chunk chunk(size, KeyValueChunk::kChunkType);
    1.95 +        chunk._keyLength = keyLength;
    1.96 +        Blob b[4] = {
    1.97 +            Blob(&chunk, sizeof(chunk._size)+sizeof(chunk._keyLength)),
    1.98 +            key,
    1.99 +            Blob(&zeros, pad),
   1.100 +            value};
   1.101 +        return file->writeMultiple(b,4);
   1.102 +    }
   1.103 +
   1.104 +    
   1.105 +    
   1.106 +    ChunkIterator::ChunkIterator (File* file, FilePosition start)
   1.107 +        :_file(file),
   1.108 +         _pos(start),
   1.109 +         _length(_file->length()),
   1.110 +         _chunk(NULL)
   1.111 +    { 
   1.112 +        _loadChunk();
   1.113 +    }
   1.114 +    
   1.115 +    void ChunkIterator::_loadChunk() {
   1.116 +        if (_pos < _length) {
   1.117 +            _chunk = (const Chunk*) _file->mappedPosition(_pos);
   1.118 +            if (_chunk->size() < sizeof(Chunk) || _pos+_chunk->size() > _length)
   1.119 +                _chunk = NULL;
   1.120 +        } else {
   1.121 +            _chunk = NULL;
   1.122 +        }
   1.123 +
   1.124 +    }
   1.125 +    
   1.126 +    bool ChunkIterator::atEOF() const {
   1.127 +        return _pos == _length;
   1.128 +    }
   1.129 +    
   1.130 +    bool ChunkIterator::next() {
   1.131 +        if (_chunk) {
   1.132 +            _pos += _chunk->size();
   1.133 +            _loadChunk();
   1.134 +        }
   1.135 +        return _chunk != NULL;
   1.136 +    }
   1.137 +    
   1.138 +}