mirror of https://github.com/dwsJason/gsla.git
273 lines
9.0 KiB
C++
273 lines
9.0 KiB
C++
//
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// C++ Encoder/Decoder
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// For GSLA, GS Lzb Animation File Format
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//
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//
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// Care is taken in the encoder, to make sure the 65816 does not have to cross
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// bank boundaries during any copy. This is so we can use the MVN instruction,
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// and so we can reduce the number of bank checks in the code. We will have an
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// opcode, that says “source data bank has changed”
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//
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// The file will be laid out such that you load the file in at a 64K memory
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// boundary
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//
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// Goals include a good balance between file size, and playback performance
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// (since one often makes a trade off with the other).
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//
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// The file is defined as a byte stream, loaded on a 64K Bank Boundary
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//
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//
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// file-offset: the thing that is at the offset
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//
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// Header of the File is 20 bytes as follows
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//
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//File Offset Data Commentary
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//------------------------------------------------------------------
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//0 0x47 ; ‘G’ Graphics
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//1 0x53 ; ‘S’
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//2 0x4C ; ‘L’ LZB
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//3 0x41 ; ‘A’ Animation
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//
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// File Length, is the total length of the file
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//4 FileLengthLow ; Low byte, 32-bit file length
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//5 LengthLowHigh ; High byte of low word
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//6 LengthHighLow ; Low byte, of high word
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//7 LengthHighHigh ; High Byte, of high word
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//
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// 16 bit word with version #
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//8 VL ; Version # of the file format, currently only version 0 exists
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//9 VH ; Version High Byte
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// ; %RVVV_VVVV_VVVV_VVVV
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// ; V is a version #, 0 for now
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// ; R is the MSB, R = 0 no ring frame
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// ; R = 1, there is a ring frame
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// ; A Ring Frame is a frame that will delta from the last
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// ; frame of the animation, back to the first, for smoother
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// ; playback looping , If a ring frame exists, it’s also
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// ; included in the frame count
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//
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// next is a word, width in bytes (likely 160 for now)
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//0xA WL ; Display Width in bytes low byte
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//0xB WH ; Display Width in bytes high byte
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//
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// next is a word, height (likely 200 for now)
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//0xC HL ; Display Height in bytes, low byte
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//0xD HH ; Display Height in bytes, high byte
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// 2 bytes, Frame Size in Bytes, since a “Frame” may contain more than just the
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// width * height, worth of pixels, for now this is $8000, or 32768
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//0xE FBL ; Frame Buffer Length Low
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//0xF FBH ; Frame Buffer Length High
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//
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// 4 byte, 32-bit, Frame Count (includes total frame count, so if there is a ring frame, this is included in the total)
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//0x10 FrameCountLow
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//0x11 FrameCountLowHigh
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//0x12 FrameCountHighLow
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//0x13 FrameCountHigh
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//
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//
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// After this comes AIFF style chunks of data, basically a 4 byte chunk name,
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// followed by a 4 byte length (inclusive of the chunk size). The idea is that
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// you can skip chunks you don’t understand.
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//
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//File Offset:
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//0x14 First Chunk (followed by more Chunks, until end of file)
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//
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//Chunk Definitions
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//Name: ‘INIT’ - Initial Frame Chunk, this is the data used to first initialize the playback buffer
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//0: 0x49 ‘I’
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//1: 0x4E ‘N’
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//2: 0x49 ‘I’
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//3: 0x54 ‘T’
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// 32 bit long, length, little endian, including the 8 byte header
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//4: length low low
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//5: length low high
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//6: length high low
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//7: length high high
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//
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//8: …. This is a single frame of data, that decodes/decompresses into frame
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// sized bytes (right now 0x8000)
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// This data stream includes, an end of animation opcode, so that the normal
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// animation decompressor, can be called on this data, and it will emit the
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// initial frame onto the screen
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//
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//Name: ‘ANIM’ - Frames
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//0: 0x41 ‘A’
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//1: 0x4E ‘N’
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//2: 0x49 ‘I’
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//3: 0x4D ‘M’
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// 32 bit long, length, little endian, including chunk header
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//4: length low low
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//5: length low high
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//6: length high low
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//7: length high high
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//
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// This is followed by the frames, with the intention of decompressing them at
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// 60FPS, which is why no play speed is included, if you need a play-rate
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// slower than this, blank frame’s should be inserted into the animation data
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//
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// Every attempt is made to delta encode the image, meaning we just encode
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// information about what changed each frame. We attempt to make the size
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// efficient by supporting dictionary copies (where the dictionary is made up
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// of existing pixels in the frame buffer).
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//
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//Command Word, encoded low-high, what the bits mean:
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//
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// xxx_xxxx_xxxx_xxx is the number of bytes 1-16384 to follow (0 == 1 byte)
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//
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//%0xxx_xxxx_xxxx_xxx0 - Copy Bytes - straight copy bytes
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//%1xxx_xxxx_xxxx_xxx1 - Skip Bytes - skip bytes / move the cursor
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//%1xxx_xxxx_xxxx_xxx0 - Dictionary Copy Bytes from frame buffer to frame buffer
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//
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//%0000_0000_0000_0001- Source Skip -> Source pointer skips to next bank of data
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//%0000_0000_0000_0011- End of Frame - end of frame
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//%0000_0000_0000_0111- End of Animation / End of File / no more frames
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//
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// other remaining codes, are reserved for future expansion
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#include "gsla_file.h"
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#include <stdio.h>
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// If these structs are the wrong size, there's an issue with type sizes, and
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// your compiler
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static_assert(sizeof(GSLA_Header)==20, "GSLA_Header is supposed to be 20 bytes");
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static_assert(sizeof(GSLA_INIT)==8, "GSLA_INIT is supposed to be 8 bytes");
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static_assert(sizeof(GSLA_ANIM)==8, "GSLA_ANIM is supposed to be 8 bytes");
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static_assert(sizeof(GSLA_CHUNK)==8, "GSLA_CHUNK is supposed to be 8 bytes");
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//------------------------------------------------------------------------------
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// Load in a FanFile constructor
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//
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GSLAFile::GSLAFile(const char *pFilePath)
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: m_widthPixels(320)
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, m_heightPixels(200)
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{
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LoadFromFile(pFilePath);
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}
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//------------------------------------------------------------------------------
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GSLAFile::~GSLAFile()
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{
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// Free Up the memory
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for (int idx = 0; idx < m_pC1PixelMaps.size(); ++idx)
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{
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delete[] m_pC1PixelMaps[idx];
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m_pC1PixelMaps[ idx ] = nullptr;
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}
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}
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//------------------------------------------------------------------------------
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void GSLAFile::LoadFromFile(const char* pFilePath)
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{
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// Free Up the memory
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for (int idx = 0; idx < m_pC1PixelMaps.size(); ++idx)
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{
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delete[] m_pC1PixelMaps[idx];
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m_pC1PixelMaps[ idx ] = nullptr;
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}
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m_pC1PixelMaps.clear();
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//--------------------------------------------------------------------------
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std::vector<unsigned char> bytes;
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//--------------------------------------------------------------------------
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// Read the file into memory
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FILE* pFile = nullptr;
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errno_t err = fopen_s(&pFile, pFilePath, "rb");
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if (0==err)
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{
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fseek(pFile, 0, SEEK_END);
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size_t length = ftell(pFile); // get file size
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fseek(pFile, 0, SEEK_SET);
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bytes.resize( length ); // make sure buffer is large enough
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// Read in the file
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fread(&bytes[0], sizeof(unsigned char), bytes.size(), pFile);
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fclose(pFile);
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}
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if (bytes.size())
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{
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size_t file_offset = 0; // File Cursor
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// Bytes are in the buffer, so let's start looking at what we have
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GSLA_Header* pHeader = (GSLA_Header*) &bytes[0];
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// Early out if things don't look right
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if (!pHeader->IsValid((unsigned int)bytes.size()))
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return;
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// Size in bytes for each frame in this animation
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m_frameSize = pHeader->frame_size;
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// pre-allocate all the frames
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for (unsigned int idx = 0; idx < pHeader->frame_count; ++idx)
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{
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m_pC1PixelMaps.push_back(new unsigned char[ m_frameSize ]);
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}
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//----------------------------------------------------------------------
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// Process Chunks as we encounter them
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file_offset += sizeof(GSLA_Header);
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// While we're not at the end of the file
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while (file_offset < bytes.size())
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{
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// This is pretty dumb, just get it done
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// These are the types I understand
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// every chunk is supposed to contain a value chunk_length
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// at offset +4, so that we can ignore ones we don't understand
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GSLA_INIT* pINIT = (GSLA_INIT*)&bytes[ file_offset ];
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GSLA_ANIM* pANIM = (GSLA_ANIM*)&bytes[ file_offset ];
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GSLA_CHUNK* pCHUNK = (GSLA_CHUNK*)&bytes[ file_offset ];
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if (pINIT->IsValid())
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{
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// We have an initial frame chunk
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UnpackInitialFrame(pINIT);
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}
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else if (pANIM->IsValid())
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{
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// We have a packed animation frames chunk
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UnpackAnimation(pANIM, pHeader);
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}
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file_offset += pCHUNK->chunk_length;
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}
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}
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}
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//------------------------------------------------------------------------------
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//------------------------------------------------------------------------------
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//
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// Unpack the initial frame, that's been packed with an empty initial dictionary
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// So every byte of the buffer will be written out (no skip opcodes)
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//
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void GSLAFile::UnpackInitialFrame(GSLA_INIT* pINIT)
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{
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unsigned char *pData = ((unsigned char*)pINIT) + sizeof(GSLA_INIT);
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unsigned char *pTargetBuffer = m_pC1PixelMaps[ 0 ]; // Data needs to be pre allocated
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//DecompressFrame(pTargetBuffer, pData);
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}
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//------------------------------------------------------------------------------
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//
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// Unpack the animation frame, assuming that the initial frame already exists
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//
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void GSLAFile::UnpackAnimation(GSLA_ANIM* pANIM, GSLA_Header* pHeader)
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{
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unsigned char *pData = ((unsigned char*)pANIM) + sizeof(GSLA_ANIM);
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unsigned char *pTargetBuffer = m_pC1PixelMaps[ 0 ]; // Data needs to be pre allocated
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//DecompressAnim(pTargetBuffer, pData);
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}
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