rle.c

Visual C++网络通信编程实用案例精逊配套源码 光盘中存放的是书中涉及的所有实例的源代码和经过编译后的应用程序。所有程序均经过测试

// Run Length 编码解码函数集
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include "RLE.h"
#include "Server.h"

DWORD	dwCodeLength = 19;

DWORD RunLength(BYTE *pInput,DWORD dwCount)
{
	DWORD	dwNewCount = 4;
	DWORD	dwMaxRun;
	DWORD	dwUnusedByte = 0;
	BOOL	fOutput = FALSE;

	__asm
	{
		MOV		EDX,1
		MOV		ECX,dwCodeLength
		SUB		ECX,9
		SHL		EDX,CL
		SUB		EDX,1
		MOV		dwMaxRun,EDX

		MOV		EDX,dwCount

		XOR		EDI,EDI

		XOR		ESI,ESI

		_LoadByte:

		PUSH	ESI

		MOV		ESI,pInput
		MOV		AL,[ESI]

		MOV		ECX,DWORD PTR 1

		_CompareBytes:

		CMP		EDX,0
		JZ		_Finished

		CMP		ECX,dwMaxRun
		JA		_Finished

		CMP		AL,[ESI + ECX]

		LEA		ECX,[ECX + 1]

		LEA		EDX,[EDX - 1]

		JE		_CompareBytes

		_Finished:

		DEC		ECX

		ADD		ESI,ECX
		MOV		pInput,ESI

		POP		ESI

		CMP		ECX,1
		JNZ		_BuildCode

		XOR		EBX,EBX
		MOV		BH,1
		MOV		BL,AL

		MOV		ECX,9

		JMP		_CheckShift

		_BuildCode:
		MOV		EBX,ECX
		SHL		EBX,8
		MOV		BL,AL

		MOV		ECX,dwCodeLength

		_CheckShift:
		ADD		EDI,ECX
		CMP		EDI,32
		JLE		_ShiftData

		SUB		EDI,32

		SUB		ECX,EDI

		MOV		dwUnusedByte,EBX

		PUSH	ECX
		MOV		ECX,EDI
		SHR		EBX,CL
		POP		ECX

		// Set the Output Flag
		MOV		fOutput,TRUE

		// Shift the Output Data
		_ShiftData:

		// Shift the Output Symbol to Handle a New Symbol
		SHL		ESI,CL

		// OR the Output Symbol with New Symbol
		OR		ESI,EBX

		// Check for Outputting a full DWORD
		CMP		fOutput,FALSE
		JE		_Continue

		// Increment the Compression Count
		ADD		dwNewCount,4

		// Remove the Bits we Used
		MOV		EAX,32
		SUB		EAX,EDI
		MOV		ECX,EAX

		// Restore the Unused Portion of the Code
		MOV		EAX,dwUnusedByte
		SHL		EAX,CL
		SHR		EAX,CL

		// Update the Code to Have the Left Over Bits
		MOV		ESI,EAX

		// Initialize the Left Over Bits
		MOV		dwUnusedByte,0

		// Reset the Output Flag
		MOV		fOutput,FALSE

		// Compare for More Data
		_Continue:
		CMP		EDX,0
		JZ		_Exit

		// Go Back for More Bytes
		JMP		_LoadByte

		// Finished Encoding
		_Exit:

		// Update Any Remaining Compression data in the Buffer
		CMP		EDI,0
		JE		_Done

		// Left Shift the Remaining Bits
		MOV		EAX,32
		SUB		EAX,EDI
		MOV		ECX,EAX
		SHL		ESI,CL

		// Increment the Compression Count
		ADD		dwNewCount,4

		// Done Encoding
		_Done:
	}

	// Return the Compressed Count
	return dwNewCount;
}

// Run Length Encode the Input Data to the Output Data
DWORD RunLengthEncode(BYTE *pInput,DWORD dwCount,BYTE *pOutput)
{
	// Compressed Count
	DWORD	dwNewCount = 4;

	// Variables Used for Code Shifting
	DWORD	dwUnusedByte = 0;
	BOOL	fOutput = FALSE;

	// Max Run Length
	DWORD	dwMaxRun;

	__asm
	{
		// Calculate the Maximum Run Length
		MOV		EDX,1
		MOV		ECX,dwCodeLength
		SUB		ECX,9
		SHL		EDX,CL
		SUB		EDX,1
		MOV		dwMaxRun,EDX

		// Point to the Input Byte
		MOV		EDI,pOutput

		// Load the Count of Bytes to Encode
		MOV		EDX,dwCount

		// Store the Original Length in the Compressed Data
		MOV		[EDI],EDX

		// Increment the Input Data Pointer
		ADD		EDI,4
		MOV		pOutput,EDI

		// Initialize the Output Bits
		XOR		EDI,EDI

		// Initialize the Storage DWORD
		XOR		ESI,ESI

		// Load the Byte to Compare
		_LoadByte:

		// Save the Storage DWORD
		PUSH	ESI

		// Load a Byte
		MOV		ESI,pInput
		MOV		AL,[ESI]

		// Initialize the Run Length Count to 1
		MOV		ECX,DWORD PTR 1

		// Compare the Bytes
		_CompareBytes:

		// Check for EOD
		CMP		EDX,0
		JZ		_Finished

		// Compare to the Max Length for an Encode
		CMP		ECX,dwMaxRun
		JA		_Finished

		// Compare the Bytes
		CMP		AL,[ESI + ECX]

		// Increment the Run Length
		LEA		ECX,[ECX + 1]

		// Decrement the Bytes Processed
		LEA		EDX,[EDX - 1]

		// Branch for the Comparison
		JE		_CompareBytes

		// Finished Encoding
		_Finished:

		// Decrement the Run Length for Encoding
		DEC		ECX

		// Increment the Pointer to the Source Data
		ADD		ESI,ECX
		MOV		pInput,ESI

		// Restore the Storage DWORD
		POP		ESI

		// Check for a 1:1 Character Copy
		CMP		ECX,1
		JNZ		_BuildCode

		// Move in the Character
		XOR		EBX,EBX
		MOV		BH,1
		MOV		BL,AL

		// Set the Code Length
		MOV		ECX,9

		// Jump to Checking the Bit Shifting
		JMP		_CheckShift

		// Build the Compression Code
		_BuildCode:
		MOV		EBX,ECX
		SHL		EBX,8
		MOV		BL,AL

		// Set the Code Length
		MOV		ECX,dwCodeLength

		// See How Many Bits Can be Shifted to the Output DWORD
		_CheckShift:
		ADD		EDI,ECX
		CMP		EDI,32
		JLE		_ShiftData

		// See How Many Bits of the Last Code Can't Be Used
		SUB		EDI,32

		// Adjust ECX to Handle only the Bits that Can Be Used
		SUB		ECX,EDI

		// Save the Code
		MOV		dwUnusedByte,EBX

		// Shift the Input Symbol to the Right
		PUSH	ECX
		MOV		ECX,EDI
		SHR		EBX,CL
		POP		ECX

		// Set the Output Flag
		MOV		fOutput,TRUE

		// Shift the Output Data
		_ShiftData:

		// Shift the Output Symbol to Handle a New Symbol
		SHL		ESI,CL

		// OR the Output Symbol with New Symbol
		OR		ESI,EBX

		// Check for Outputting a full DWORD
		CMP		fOutput,FALSE
		JE		_Continue

		// Output an Encoded Symbol
		MOV		EAX,ESI
		PUSH	EDI
		MOV		EDI,pOutput
		MOV		[EDI],EAX
		ADD		EDI,4
		MOV		pOutput,EDI
		POP		EDI

		// Increment the Compression Count
		ADD		dwNewCount,4

		// Remove the Bits we Used
		MOV		EAX,32
		SUB		EAX,EDI
		MOV		ECX,EAX

		// Restore the Unused Portion of the Code
		MOV		EAX,dwUnusedByte
		SHL		EAX,CL
		SHR		EAX,CL

		// Update the Code to Have the Left Over Bits
		MOV		ESI,EAX

		// Initialize the Left Over Bits
		MOV		dwUnusedByte,0

		// Reset the Output Flag
		MOV		fOutput,FALSE

		// Compare for More Data
		_Continue:
		CMP		EDX,0
		JZ		_Exit

		// Go Back for More Bytes
		JMP		_LoadByte

		// Finished Encoding
		_Exit:

		// Update Any Remaining Compression data in the Buffer
		CMP		EDI,0
		JE		_Done

		// Left Shift the Remaining Bits
		MOV		EAX,32
		SUB		EAX,EDI
		MOV		ECX,EAX
		SHL		ESI,CL

		// Output the Final Encoded Symbol
		MOV		EAX,ESI
		MOV		EDI,pOutput
		MOV		[EDI],EAX

		// Increment the Compression Count
		ADD		dwNewCount,4

		// Done Encoding
		_Done:
	}

	// Return the Compressed Count
	return dwNewCount;
}

// Run Length Decode the Input Data to the Output Data
DWORD RunLengthDecode(BYTE *pInput,BYTE *pOutput)
{
	// Compressed Count
	DWORD	dwCount;
	DWORD	dwCompCount;
	DWORD	dwCodeLength2;

	__asm
	{
		// Get the CodeLength - 1 for Checking a 1:1 Compression
		MOV		EAX,dwCodeLength
		DEC		EAX
		MOV		dwCodeLength2,EAX

		// Point to the Input Byte
		MOV		ESI,pInput

		// Point to the Output Byte
		MOV		EDI,pOutput

		// Load the Count of Bytes Encoded
		LODSD

		// Save the New Input Location
		MOV		pInput,ESI

		// Save the Count of the UnCompressed Data
		MOV		dwCompCount,EAX

		// Initialize the Count of Bytes Decoded
		MOV		dwCount,EAX

		// Initialize Number of Bits for Current Symbol to Process
		MOV		ESI,dwCodeLength

		// Initialize the Decode Storage
		XOR		EDX,EDX

		// Main Loop for Reading Input
		_LoopInput:

		// Save the Number of Bits for the Current Symbol
		PUSH	ESI

		// Point to the Input Data
		MOV		ESI,pInput

		// Read an Encoded DWORD
		LODSD

		// Save the Pointer to the Input Data
		MOV		pInput,ESI

		// Restore the Number of Bits for the Current Symbol
		POP		ESI

		// Initialize Number of Bits to Process
		MOV		EBX,32

		// Shift in an Encoded Symbol, 1 bit at a time
		_LeftShift:

		// Shift 1 Bit of the Input Code to the Output
		SHLD	EDX,EAX,1

		// Shift the Input Code 1 Bit to the Left
		SHL		EAX,1

		// Decrement the Number of Bits Processed
		DEC		ESI

		// Check for a Fully Encoded Symbol
		JZ		_Output

		// Compare the High Bit for RLE or Character Encode
		CMP		ESI,dwCodeLength2
		JNZ		_CheckBits

		// Compare the High Bit, 0 = RLE, 1 = 1:1 Character Encode
		CMP		EDX,0
		JZ		_CheckBits

		// Update the Bits Left to 8
		MOV		ESI,8

		// Check for More Bits to Process
		_CheckBits:

		// Decrement the Number of Bits Processed in the Input DWORD
		DEC		EBX

		// Continue Shifting More Bits
		JNZ		_LeftShift

		// Read Another DWORD of Data
		JMP		_LoopInput

		// Output the Run Length Amount of the Code
		_Output:

		// Get the Run Length
		MOV		ECX,EDX
		SHR		ECX,8

		// Get the Code
		AND		EDX,255

		// Save the Input DWORD
		PUSH	EAX

		// Copy the Code
		MOV		EAX,EDX

		// Save the Run Length
		PUSH	ECX

		// Output the Run Length Amount of the Code
		REP		STOSB

		// Restore the Run Length
		POP		ECX

		// Restore the Input DWORD
		POP		EAX

		// Check for More Data to Decode
		SUB		dwCompCount,ECX
		JZ		_Exit

		// Initialize the Decode Storage
		XOR		EDX,EDX

		// Initialize Number of Bits for Current Symbol to Process
		MOV		ESI,dwCodeLength

		// Check for More Bits to Process
		JMP		_CheckBits

		// Finished
		_Exit:
	}

	// Return the Count of Uncompressed Data
	return dwCount;
}