383 lines
17 KiB
C++
383 lines
17 KiB
C++
/**************************** omfhash.cpp **********************************
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* Author: Agner Fog
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* Date created: 2007-02-14
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* Last modified: 2007-02-14
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* Project: objconv
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* Module: omfhash.cpp
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* Description:
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* This module contains code for searching and making hash tables for OMF
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* libraries.
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*
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* Copyright 2007-2008 GNU General Public License http://www.gnu.org/licenses
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*****************************************************************************/
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#include "stdafx.h"
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void COMFHashTable::Init(SOMFHashBlock * blocks, uint32 NumBlocks) {
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// Initialize
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this->blocks = blocks; // Pointer to blocks
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this->NumBlocks = NumBlocks; // Number of blocks
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String = 0;
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StringLength = 0;
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}
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// Rotate right 16-bit word
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uint16 RotR(uint16 x, uint16 bits) {
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return (x >> bits) | (x << (16 - bits));
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}
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// Rotate left 16-bit word
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uint16 RotL(uint16 x, uint16 bits) {
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return (x << bits) | (x >> (16 - bits));
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}
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void COMFHashTable::MakeHash(int8 * name) {
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// Compute hash according to the official algorithm
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uint8 * pb; // Pointer for forward scan through string
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uint8 * pe; // Pointer for backwards scan through string
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uint16 c; // Current character converted to lower case
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uint16 BlockX; // Calculate block hash
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uint16 BucketX; // Calculate block hash
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String = (uint8*)name; // Type cast string to unsigned char *
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StringLength = (uint32)strlen(name);
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if (StringLength > 255 || StringLength == 0) {
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// String too long
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err.submit(1204, name); // Warning: truncating
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StringLength = 255;
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String[StringLength] = 0; // Truncation modifies string source!
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}
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String = (uint8*)name; // Type cast to unsigned characters
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pb = String; // Initialize pointer for forward scan
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pe = String + StringLength; // Initialize pointer for backward scan
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BlockX = BucketD = StringLength | 0x20; // Initialize left-to-right scan
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BucketX = BlockD = 0; // Initialize right-to-left scan
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// Scan loop
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while (1) {
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c = *(--pe) | 0x20; // Read character for backward scan, make lower case
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BucketX = RotR(BucketX, 2) ^ c; // Rotate, XOR
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BlockD = RotL(BlockD, 2) ^ c; // Rotate, XOR
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if (pe == String) break; // Stop loop when backward scan finished
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c = *(pb++) | 0x20; // Read character for forward scan, make lower case
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BlockX = RotL(BlockX, 2) ^ c; // Rotate, XOR
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BucketD = RotR(BucketD, 2) ^ c; // Rotate, XOR
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}
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// Make values modulo number of blocks / buckets
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BlockX = BlockX % NumBlocks;
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BlockD = BlockD % NumBlocks;
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if (BlockD == 0) BlockD = 1;
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BucketX = BucketX % OMFNumBuckets;
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BucketD = BucketD % OMFNumBuckets;
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if (BucketD == 0) BucketD = 1;
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StartBlock = BlockX;
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StartBucket = BucketX;
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}
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int COMFHashTable::FindString(uint32 & ModulePage, uint32 & Conflicts) {
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// Search for String.
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// Returns number of occurrences of String
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// Module receives the module page for the first occurrence
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// Conflicts receives the number of conflicting entries encountered before the match
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uint32 Num = 0; // Number of occurrences of string found
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uint16 Block; // Block number
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uint16 Bucket; // Bucket number
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uint32 StringIndex; // Index to string
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Conflicts = 0; // Start counting Conflicts
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Block = StartBlock;
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Bucket = StartBucket;
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// Loop through blocks
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do {
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// Loop through buckets
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do {
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// String index of current bucket
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StringIndex = blocks[Block].b.Buckets[Bucket];
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if (StringIndex == 0) {
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if (blocks[Block].b.FreeSpace < 0xff) {
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// Empty bucket found. End of search
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return Num;
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}
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else {
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// Block is full. Search next block
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// Note: It would be logical to set StartBucket = Bucket
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// here in order to allow all buckets in the next block
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// to be tried, but the official algorithm doesn't seem
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// to do so!?
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// StartBucket = Bucket;
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break;
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}
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}
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// Bucket contains a string. Is it the same string?
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if (blocks[Block].Strings[StringIndex*2] == StringLength
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&& strncmp((int8*)&blocks[Block].Strings[StringIndex*2+1], (int8*)String, StringLength) == 0) {
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// Matching string found
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Num++;
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if (Num == 1) {
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// First occurrence. Save module number
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ModulePage = *(uint16*)&blocks[Block].Strings[StringIndex*2+1+StringLength];
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}
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}
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else {
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// Conflicting string found
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Conflicts++;
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}
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// Next bucket
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Bucket = (Bucket + BucketD) % OMFNumBuckets;
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} while (Bucket != StartBucket);
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// Next block
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Block = (Block + BlockD) % NumBlocks;
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} while (Block != StartBlock);
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// Finished searching all blocks and buckets
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return Num;
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}
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int COMFHashTable::InsertString(uint16 & ModulePage) {
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// Insert string in hash table.
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// Parameter:
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// ModulePage = module address / page size
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// Return value:
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// 0 if success,
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// 1 if identical string allready exists in the table. New string will not be entered.
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// ModulePage will receive the module page of the existing string in this case.
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// 2 if table is full,
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uint16 Block; // Block number
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uint16 Bucket; // Bucket number
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uint32 StringIndex; // Index to string space
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uint32 StringOffset; // Offset to string from begin of block
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uint32 SpaceRequired; // Space required to store string
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SpaceRequired = StringLength + 3; // Space for string + stringlength + module index
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SpaceRequired = (SpaceRequired + 1) & uint32(-2);// Round up to nearest even
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Block = StartBlock;
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Bucket = StartBucket;
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// Loop through blocks
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do {
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// Loop through buckets
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do {
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// String index of current bucket
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StringIndex = blocks[Block].b.Buckets[Bucket];
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if (StringIndex == 0) {
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// Found empty bucket. Check if block has enough free space
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if (uint32(OMFBlockSize) - blocks[Block].b.FreeSpace * 2 < SpaceRequired) {
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// Not enough space in block.
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// Continue with same bucket in next block.
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// Note: It would be logical to set StartBucket = Bucket
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// here in order to allow all buckets in the next block
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// to be tried, but the official algorithm doesn't seem
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// to do so!?
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// StartBucket = Bucket;
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break;
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}
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// Enough space found. Enter string in bucket
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StringIndex = blocks[Block].b.FreeSpace;
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blocks[Block].b.Buckets[Bucket] = StringIndex;
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// Address to store string
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StringOffset = StringIndex * 2;
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// Store string length
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blocks[Block].Strings[StringOffset] = (uint8)StringLength;
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// Copy string
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memcpy(blocks[Block].Strings + StringOffset + 1, String, StringLength);
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// Insert module page number
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*(uint16*)(blocks[Block].Strings + StringOffset + 1 + StringLength) = ModulePage;
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// Update free space
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blocks[Block].b.FreeSpace += (uint8)(SpaceRequired / 2);
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// Check if overflow
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if (blocks[Block].b.FreeSpace == 0) blocks[Block].b.FreeSpace = 0xFF;
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// Indicate success
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return 0;
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}
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else {
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// Bucket contains a string. Check if it is the same string
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if (blocks[Block].Strings[StringIndex*2] == StringLength
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&& strncmp((int8*)(blocks[Block].Strings+StringIndex*2+1), (int8*)String, StringLength) == 0) {
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// Identical string found. Return module index for existing string entry
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ModulePage = *(uint16*)(blocks[Block].Strings+StringIndex*2+1+StringLength);
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// Indicate failure
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return 1;
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}
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}
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// Bucket was full. Go to next bucket
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Bucket = (Bucket + BucketD) % OMFNumBuckets;
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} while (Bucket != StartBucket);
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// If we got here, we have found no empty bucket in the block or
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// there was not enough string space in the block.
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// We need to mark the block as full to tell the linker to
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// continue in next block when searching for this string
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// Whether the block has any empty buckets or not
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blocks[Block].b.FreeSpace = 0xFF;
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// Go to next block
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Block = (Block + BlockD) % NumBlocks;
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} while (Block != StartBlock);
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// Finished searching all blocks and buckets
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// No empty space found. Indicate failure:
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return 2;
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}
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// Table of prime numbers
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// You may add more prime numbers if very big library files are needed
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static const uint32 PrimeNumbers[] = {
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1, 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71,
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73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157,
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163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241,
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251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347,
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349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439,
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443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547,
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557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643,
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647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751,
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757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859,
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863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977,
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983, 991, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063,
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1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163,
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1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259,
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1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361,
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1367, 1373, 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453,
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1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549,
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1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621,
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1627, 1637, 1657, 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733,
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1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847,
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1861, 1867, 1871, 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949,
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1951, 1973, 1979, 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039,
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2053, 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, 2131, 2137,
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2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243, 2251,
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2267, 2269, 2273, 2281, 2287, 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347,
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2351, 2357, 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, 2437,
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2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551,
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2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633, 2647, 2657, 2659, 2663, 2671,
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2677, 2683, 2687, 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741,
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2749, 2753, 2767, 2777, 2789, 2791, 2797, 2801, 2803, 2819, 2833, 2837, 2843,
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2851, 2857, 2861, 2879, 2887, 2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957,
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2963, 2969, 2971, 2999, 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067,
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3079, 3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187, 3191,
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3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271, 3299, 3301, 3307,
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3313, 3319, 3323, 3329, 3331, 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391,
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3407, 3413, 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511, 3517,
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3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583, 3593, 3607,
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3613, 3617, 3623, 3631, 3637, 3643, 3659, 3671, 3673, 3677, 3691, 3697, 3701,
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3709, 3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821,
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3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889, 3907, 3911, 3917, 3919,
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3923, 3929, 3931, 3943, 3947, 3967, 3989, 4001, 4003, 4007, 4013, 4019, 4021,
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4027, 4049, 4051, 4057, 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133,
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4139, 4153, 4157, 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243,
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4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349, 4357,
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4363, 4373, 4391, 4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481,
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4483, 4493, 4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, 4591,
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4597, 4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657, 4663, 4673, 4679, 4691,
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4703, 4721, 4723, 4729, 4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799, 4801,
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4813, 4817, 4831, 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937,
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4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003, 5009, 5011, 5021
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};
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// Length of table
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static const uint32 PrimeNumbersLen = sizeof(PrimeNumbers)/sizeof(PrimeNumbers[0]);
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void COMFHashTable::MakeHashTable(CSList<SStringEntry> & StringEntries,
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CMemoryBuffer & StringBuffer, CMemoryBuffer & OutFile, CLibrary * Library) {
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// Make hash table. Parameters:
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// StringEntries[].String = name of each public symbol as offset into StringBuffer
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// StringEntries[].Member = page address of member = offset / page size
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// StringBuffer = contains all strings
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// OutFile will receive the output hash table
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CSList<SOMFHashBlock> HashTable; // Hash table
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COMFHashTable TableHandler; // Hash table handler
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uint32 NumBlocksI; // Number of blocks as index into prime number table
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uint32 BlockI; // Block index
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uint32 SymI; // Symbol index
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int8 * String; // Symbol name
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uint16 Module1, Module2; // Module page = offset / page size
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int Result; // 0 = success
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// Estimate required number of blocks
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NumBlocks = (StringEntries.GetNumEntries() * 8 + StringBuffer.GetDataSize()) / 256;
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// Find nearest prime number >= NumBlocks, but stay within the range from 2 to 251.
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// The minimum NumBlocks is 1, but some systems use 2 as the minimum.
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// The maximum is 251, but some linkers may allow a higher number
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for (NumBlocksI = 1; NumBlocksI < 55; NumBlocksI++) {
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if (PrimeNumbers[NumBlocksI] >= NumBlocks) break;
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}
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// Try if this number of blocks is sufficient
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while (NumBlocksI < PrimeNumbersLen) {
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// Get number of blocks from prime numbers table
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NumBlocks = PrimeNumbers[NumBlocksI];
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// Check if <= 251
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if (NumBlocks > 255) err.submit(1215); // Number of blocks exceeds official limit. May still work with some linkers
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// Allocate space for hash table
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HashTable.SetNum(NumBlocks);
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memset(&HashTable[0], 0, NumBlocks * OMFBlockSize);
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// Initialize hash table handler
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TableHandler.Init(&HashTable[0], NumBlocks);
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// Set free space pointers
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for (BlockI = 0; BlockI < NumBlocks; BlockI++) {
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TableHandler.blocks[BlockI].b.FreeSpace = 19;
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}
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Result = 0;
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// Insert symbols
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// Loop through symbols
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for (SymI = 0; SymI < StringEntries.GetNumEntries(); SymI++) {
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// Symbol name
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String = StringBuffer.Buf() + StringEntries[SymI].String;
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// Module page
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Module1 = Module2 = StringEntries[SymI].Member;
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// Insert name in table
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TableHandler.MakeHash(String);
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Result = TableHandler.InsertString(Module2);
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if (Result == 1) {
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// String already exists
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// Compose error string "Modulename1 and Modulename2"
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char ErrorModuleNames[64];
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strcpy(ErrorModuleNames, Library->GetModuleName(Module1));
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strcpy(ErrorModuleNames + strlen(ErrorModuleNames), " and ");
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strcpy(ErrorModuleNames + strlen(ErrorModuleNames), Library->GetModuleName(Module2));
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// submit error message
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err.submit(1214, String, ErrorModuleNames);
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}
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if (Result == 2) {
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// Table is full. Stop and repeat with a higher NumBlocks
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break;
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}
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} // End of loop through symbols
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if (Result < 2) {
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// Finished with success
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// Store hash table
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OutFile.Push(&HashTable[0], HashTable.GetNumEntries() * OMFBlockSize);
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return;
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}
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// Table is full. Try again with a higher number of blocks
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NumBlocksI++;
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}
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// End of loop through PrimeNumbers table
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err.submit(2605); // Failed to make table
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}
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