/*
 *   symbfile.c
 *
 *   This file is part of Emu48
 *
 *   Copyright (C) 2008 Christoph Gießelink
 *
 */
#include "pch.h"
#include "Emu48.h"

//################
//#
//#    Saturn Object File Reading
//#
//################

#define RECORD_BLOCK	256					// block size
#define OS_RESOLVED		0x8000				// resolved symbol
#define OS_RELOCATABLE	0x4000				// relocatable symbol

#define SAT_ID			"Saturn3"			// saturn block header
#define SYMB_ID			"Symb"				// symbol block header

#define HASHENTRIES		199					// size of hash table

typedef struct RefData
{
	LPTSTR lpszName;						// symbol name
	DWORD  dwAddr;							// resolved address
	struct RefData* pNext;
} RefData;

static RefData *ppsBase[HASHENTRIES];		// base of symbol references (initialized with NULL)

static __inline DWORD GetHash(DWORD dwVal)
{
	return dwVal % HASHENTRIES;				// hash function
}

static DWORD GetBigEndian(LPBYTE pbyData, INT nSize)
{
	DWORD dwVal = 0;

	while (nSize-- > 0)
	{
		dwVal <<= 8;
		dwVal += *pbyData++;
	}
	return dwVal;
}

//
// check if entry table is empty
//
BOOL RplTableEmpty(VOID)
{
	DWORD i;

	BOOL bEmpty = TRUE;

	// check if hash table is empty
	for (i = 0; bEmpty && i < ARRAYSIZEOF(ppsBase); ++i)
	{
		bEmpty = (ppsBase[i] == NULL);		// check if empty
	}
	return bEmpty;
}

//
// load entry table
//
BOOL RplLoadTable(LPCTSTR lpszFilename)
{
	BYTE     byPage[RECORD_BLOCK];			// record page size
	HANDLE   hFile;
	DWORD    dwFileLength,dwCodeLength,dwNoSymbols,dwNoReferences;
	DWORD    dwBytesRead,dwSymb,dwPageIndex,dwResolvedSymb;
	BOOL     bSymbol;

	hFile = CreateFile(lpszFilename,GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,FILE_FLAG_SEQUENTIAL_SCAN,NULL);
	if (hFile == INVALID_HANDLE_VALUE)
	{
		RplDeleteTable();					// delete current table
		return FALSE;
	}

	// read first page
	ReadFile(hFile,byPage,sizeof(byPage),&dwBytesRead,NULL);
	if (   dwBytesRead != sizeof(byPage)
		|| memcmp(byPage,SAT_ID,7) != 0)
	{
		RplDeleteTable();					// delete current table
		CloseHandle(hFile);
		return FALSE;
	}

	// file length in bytes
	dwFileLength = GetBigEndian(byPage+7,sizeof(WORD)) * sizeof(byPage);

	// code area in nibbles
	dwCodeLength = GetBigEndian(byPage+9,sizeof(DWORD));

	// no. of symbols & references
	dwNoSymbols = GetBigEndian(byPage+13,sizeof(WORD));

	// no. of references
	dwNoReferences = GetBigEndian(byPage+15,sizeof(WORD));

	// convert code area length into no. of pages
	dwPageIndex = (dwCodeLength + (2 * sizeof(byPage) - 1)) / (2 * sizeof(byPage));

	// jump to begin of symbols by skipping no. of code pages
	if (SetFilePointer(hFile,dwPageIndex*sizeof(byPage),NULL,FILE_CURRENT) == INVALID_SET_FILE_POINTER)
	{
		RplDeleteTable();					// delete current table
		CloseHandle(hFile);
		return FALSE;
	}

	dwResolvedSymb = 0;						// no resolved symbols added
	bSymbol = TRUE;							// next set is a symbol

	// read all symbol pages
	for (dwPageIndex = 256, dwSymb = 0; dwSymb < dwNoSymbols; dwPageIndex += 42)
	{
		if (dwPageIndex >= 256)				// read complete page
		{
			// read new symbol page
			ReadFile(hFile,byPage,sizeof(byPage),&dwBytesRead,NULL);
			if (   dwBytesRead != sizeof(byPage)
				|| memcmp(byPage,SYMB_ID,4) != 0)
			{
				RplDeleteTable();			// delete current table
				CloseHandle(hFile);
				return FALSE;
			}

			dwPageIndex = 4;				// begin of new symbol
		}

		if (bSymbol)						// this is the 42 byte symbol set
		{
			WORD wSymbolType = (WORD) GetBigEndian(byPage+dwPageIndex+36,sizeof(WORD));

			// check if it's a resolved or relocatable symbol
			bSymbol = (wSymbolType & OS_RESOLVED) != 0;

			if (bSymbol) ++dwResolvedSymb;	// added resolved symbol

			if (wSymbolType == OS_RESOLVED)	// resolved symbol type
			{
				TCHAR szSymbolName[36+1],*pcPtr;
				RefData *pData;
				DWORD dwHash;

				#if defined _UNICODE
				{
					MultiByteToWideChar(CP_ACP, MB_PRECOMPOSED,byPage+dwPageIndex,36,
										szSymbolName,ARRAYSIZEOF(szSymbolName));
					szSymbolName[36] = 0;	// set EOS
				}
				#else
				{
					lstrcpyn(szSymbolName,byPage+dwPageIndex,ARRAYSIZEOF(szSymbolName));
				}
				#endif

				// cut symbol name at first space character
				if ((pcPtr = _tcschr(szSymbolName,_T(' '))) != NULL)
					*pcPtr = 0;				// set EOS

				// allocate symbol memory
				VERIFY(pData = HeapAlloc(hHeap,0,sizeof(RefData)));
				pData->lpszName = DuplicateString(szSymbolName);
				pData->dwAddr = GetBigEndian(byPage+dwPageIndex+38,sizeof(DWORD));

				// add to hash table
				dwHash = GetHash(pData->dwAddr);
				pData->pNext = ppsBase[dwHash];
				ppsBase[dwHash] = pData;
			}

			 ++dwSymb;						// got symbol
		}
		else								// 42 byte fill reference
		{
			bSymbol = TRUE;					// nothing to do, next is a symbol set
		}
	}

	_ASSERT(dwResolvedSymb == (dwNoSymbols - dwNoReferences));

	CloseHandle(hFile);
	return TRUE;
}

//
// delete entry table
//
VOID RplDeleteTable(VOID)
{
	RefData *pData;
	DWORD i;

	// clear hash entries
	for (i = 0; i < ARRAYSIZEOF(ppsBase); ++i)
	{
		while (ppsBase[i] != NULL)			// walk through all datasets
		{
			pData = ppsBase[i]->pNext;
			HeapFree(hHeap,0,ppsBase[i]->lpszName);
			HeapFree(hHeap,0,ppsBase[i]);
			ppsBase[i] = pData;
		}
	}
	return;
}

//
// return name for given entry address
//
LPCTSTR RplGetName(DWORD dwAddr)
{
	RefData *pData = ppsBase[GetHash(dwAddr)];

	// walk through all datasets of hash entry
	for (; pData != NULL; pData = pData->pNext)
	{
		if (pData->dwAddr == dwAddr)		// found address
			return pData->lpszName;			// return symbol name
	}
	return NULL;
}

//
// return entry address for given name
//
BOOL RplGetAddr(LPCTSTR lpszName, DWORD *pdwAddr)
{
	RefData *pData;
	DWORD   i;

	// check for every dataset in hash table
	for (i = 0; i < ARRAYSIZEOF(ppsBase); ++i)
	{
		// walk through all datasets of hash entry
		for (pData = ppsBase[i]; pData != NULL; pData = pData->pNext)
		{
			// found symbol name
			if (lstrcmp(lpszName,pData->lpszName) == 0)
			{
				*pdwAddr = pData->dwAddr;	// return address
				return FALSE;				// found
			}
		}
	}
	return TRUE;							// not found
}