wordclock/games/tetris/bucket.c

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdint.h>
#include "../../config.h"
#include "bucket.h"
#include "piece.h"


/***************************
 * non-interface functions *
 ***************************/

/**
 * determines if piece is either hovering or gliding
 * @param pBucket the bucket we want information from
 * @return TETRIS_PFS_HOVERING or TETRIS_PFS_GLIDING
 */
tetris_bucket_status_t tetris_bucket_hoverStatus(tetris_bucket_t* pBucket)
{
	// if the piece touches the dump we ensure that the status is "gliding"
	if (tetris_bucket_collision(pBucket, pBucket->nColumn, pBucket->nRow + 1))
	{
		return TETRIS_BUS_GLIDING;
	}
	// otherwise the status must be "hovering"
	else
	{
		return TETRIS_BUS_HOVERING;
	}
}


/****************************
 * construction/destruction *
 ****************************/

tetris_bucket_t *tetris_bucket_construct(int8_t nWidth,
                                         int8_t nHeight)
{
	assert((nWidth >= 4) && (nWidth <= 16));
	assert((nHeight >= 4) && (nHeight <= 124));

	tetris_bucket_t *pBucket =
			(tetris_bucket_t *)malloc(sizeof(tetris_bucket_t));

	if (pBucket != NULL)
	{
		// allocating memory for dump array
		pBucket->dump = (uint16_t*) calloc(nHeight, sizeof(uint16_t));

		if (pBucket->dump != NULL)
		{
			// setting requested attributes
			pBucket->nFirstMatterRow = nHeight - 1;
			pBucket->nWidth = nWidth;
			pBucket->nHeight = nHeight;
			tetris_bucket_reset(pBucket);

			return pBucket;
		}
		else
		{
			free(pBucket);
			pBucket = NULL;
		}
	}
	return NULL;
}


void tetris_bucket_destruct(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);

	// if memory for the dump array has been allocated, free it
	if (pBucket->dump != NULL)
	{
		free(pBucket->dump);
	}
	free(pBucket);
}


/*******************************
 * bucket related functions *
 *******************************/

uint8_t tetris_bucket_calculateLines(uint8_t nRowMask)
{
	uint8_t nMask = 0x0001;
	uint8_t nLines = 0;
	for (uint8_t i = 0; i < 4; ++i)
	{
		if ((nMask & nRowMask) != 0)
		{
			++nLines;
		}
		nMask <<= 1;
	}

	return nLines;
}


void tetris_bucket_reset(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);

	pBucket->pPiece = NULL;
	pBucket->nColumn = 0;
	pBucket->nRow = 0;
	pBucket->nRowMask = 0;

	// clear dump if it has been allocated in memory
	if (pBucket->dump != NULL)
	{
		memset(pBucket->dump, 0, pBucket->nHeight);
	}

	pBucket->status = TETRIS_BUS_READY;
}


int8_t tetris_bucket_getPieceStartPos(tetris_piece_t *pPiece)
{
	// set vertical start position (first piece row with matter at pos. 1)
	uint16_t nPieceMap = tetris_piece_getBitmap(pPiece);
	uint16_t nElementMask = 0xF000;
	int8_t nRow = -3;
	while ((nPieceMap & nElementMask) == 0)
	{
		++nRow;
		nElementMask >>= 4;
	}
	if (nRow < 0)
	{
		++nRow;
	}

	return nRow;
}


void tetris_bucket_insertPiece(tetris_bucket_t *pBucket,
                               tetris_piece_t *pPiece,
                               tetris_piece_t **ppOldPiece)
{
	assert((pBucket != NULL) && (pPiece != NULL) && (ppOldPiece != NULL));

	// a piece can only be inserted in state TETRIS_PFS_READY
	assert(pBucket->status == TETRIS_BUS_READY);

	// row mask is now meaningless
	pBucket->nRowMask = 0;

	// replace old piece
	*ppOldPiece = pBucket->pPiece;
	pBucket->pPiece = pPiece;

	// set horizontal start position (in the middle of the top line)
	pBucket->nColumn = (pBucket->nWidth - 2) / 2;

	// set vertical start position (first piece row with matter at pos. 1)
	pBucket->nRow = tetris_bucket_getPieceStartPos(pBucket->pPiece);

	// did we already collide with something?
	if (tetris_bucket_collision(pBucket, pBucket->nColumn, pBucket->nRow) == 1)
	{
		// game over man, game over!!
		pBucket->status = TETRIS_BUS_GAMEOVER;
	}
	else
	{
		// bring it on!
		pBucket->status = tetris_bucket_hoverStatus(pBucket);
	}
}


uint8_t tetris_bucket_collision(tetris_bucket_t *pBucket,
                                int8_t nColumn,
                                int8_t nRow)
{
	assert(pBucket != NULL);

	// only allow coordinates which are within sane ranges
	assert((nColumn > -4) && (nColumn < pBucket->nWidth));
	assert((nRow > -4) && (nRow < pBucket->nHeight));

	// The rows of a piece get compared with the background one by one
	// until either a collision occures or all rows are compared. Both the
	// piece row and the part of the bucket it covers are represented in
	// 4 bits which were singled out from their corresponding uint16_t
	// values and are aligned to LSB. In case where a piece overlaps with
	// either the left or the right border we "enhance" the bucket part
	// via bit shifting and set all bits representing the border to 1.
	//
	// NOTE: LSB represents the left most position.
	uint16_t nPieceMap = tetris_piece_getBitmap(pBucket->pPiece);
	uint16_t nBucketPart;
	uint16_t nPieceRowMap;

	// negative nRow values indicate that the piece hasn't fully entered the
	// bucket yet which requires special treatment if the piece overlaps
	// with either the left or the right border
	if (nRow < 0)
	{
		uint16_t nBorderMask = 0x0000;
		// piece overlaps with left border
		if (nColumn < 0)
		{
			nBorderMask = 0x1111 << (-nColumn - 1);
		}
		// piece overlaps with right border
		else if ((nColumn + 3) >= pBucket->nWidth)
		{
			nBorderMask = 0x8888 >> ((nColumn + 3) - pBucket->nWidth);
		}
		// return if piece collides with border
		if ((nPieceMap & nBorderMask) != 0)
		{
			return 1;
		}
	}

	// here we check the part which has already entered the bucket
	for (int8_t y = (nRow < 0) ? -nRow : 0; y < 4; ++y)
	{
		// current piece row overlaps with lower border
		if ((y + nRow) >= pBucket->nHeight)
		{
			// all 4 bits represent the lower border
			nBucketPart = 0x000F;
		}
		// piece overlaps with left border
		else if (nColumn < 0)
		{
			// clear all bits we are not interested in
			nBucketPart = (pBucket->dump[y + nRow] & (0x000F >> -nColumn));
			// add zeros to the left (the bits "behind" the left border)
			nBucketPart <<= -nColumn;
			// set bits beyond left border to 1
			nBucketPart |= 0x000F >> (4 + nColumn);
		}
		// piece overlaps with right border
		else if ((nColumn + 3) >= pBucket->nWidth)
		{
			// align the bits we are interested in to LSB
			// (thereby clearing the rest)
			nBucketPart = pBucket->dump[y + nRow] >> nColumn;
			// set bits beyond right border to 1
			nBucketPart |= 0xFFF8 >> (nColumn + 3 - pBucket->nWidth);
		}
		// current row neither overlaps with left, right nor lower border
		else
		{
			// clear all bits we are not interested in and align the
			// remaing row to LSB
			nBucketPart =
				(pBucket->dump[y + nRow] & (0x000F << nColumn)) >> nColumn;
		}

		// clear all bits of the piece we are not interested in and
		// align the remaing row to LSB
		nPieceRowMap = (nPieceMap & (0x000F << (y << 2))) >> (y << 2);

		// finally check for a collision
		if ((nBucketPart & nPieceRowMap) != 0)
		{
			return 1;
		}
	}

	// if we reach here, no collision was detected
	return 0;
}


void tetris_bucket_advancePiece(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);

	// a piece can only be lowered if it is hovering or gliding
	assert ((pBucket->status == TETRIS_BUS_HOVERING) ||
		(pBucket->status == TETRIS_BUS_GLIDING));

	if (tetris_bucket_collision(pBucket, pBucket->nColumn, pBucket->nRow + 1))
	{
		uint16_t nPiece = tetris_piece_getBitmap(pBucket->pPiece);

		// Is the bucket filled up?
		if ((pBucket->nRow < 0) &&
				(nPiece & (0x0FFF >> ((3 + pBucket->nRow) << 2))) != 0)
		{
			pBucket->status = TETRIS_BUS_GAMEOVER;
		}
		else
		{
			// determine valid start point for dump index
			int8_t nStartRow = ((pBucket->nRow + 3) < pBucket->nHeight) ?
				(pBucket->nRow + 3) : pBucket->nHeight - 1;
			for (int8_t i = nStartRow; i >= pBucket->nRow; --i)
			{
				int8_t y = i - pBucket->nRow;

				// clear all bits of the piece we are not interested in and
				// align the rest to LSB
				uint16_t nPieceMap = (nPiece & (0x000F << (y << 2))) >> (y << 2);
				// shift the remaining content to the current column
				if (pBucket->nColumn >= 0)
				{
					nPieceMap <<= pBucket->nColumn;
				}
				else
				{
					nPieceMap >>= -pBucket->nColumn;
				}
				// embed piece in bucket
				pBucket->dump[i] |= nPieceMap;
			}

			// update value for the highest row with matter
			int8_t nPieceRow = pBucket->nRow;
			uint16_t nMask = 0x000F;
			for (int i = 0; i < 4; ++i, nMask <<= 4)
			{
				if ((nMask & nPiece) != 0)
				{
					nPieceRow += i;
					break;
				}
			}
			pBucket->nFirstMatterRow = (pBucket->nFirstMatterRow > nPieceRow) ?
					nPieceRow : pBucket->nFirstMatterRow;

			// the piece has finally been docked
			pBucket->status = TETRIS_BUS_DOCKED;
		}
	}
	else
	{
		// since there is no collision the piece may continue its travel
		// to the ground...
		pBucket->nRow++;

		// are we gliding?
		pBucket->status = tetris_bucket_hoverStatus(pBucket);
	}
}


uint8_t tetris_bucket_movePiece(tetris_bucket_t *pBucket,
                                tetris_bucket_direction_t direction)
{
	assert(pBucket != NULL);

	// a piece can only be moved if it is still hovering or gliding
	assert((pBucket->status == TETRIS_BUS_HOVERING) ||
		(pBucket->status == TETRIS_BUS_GLIDING));

	int8_t nOffset = (direction == TETRIS_BUD_LEFT) ? -1 : 1;
	if (tetris_bucket_collision(pBucket, pBucket->nColumn + nOffset,
			pBucket->nRow) == 0)
	{
		pBucket->nColumn += nOffset;

		// are we gliding?
		pBucket->status = tetris_bucket_hoverStatus(pBucket);
		return 1;
	}

	return 0;
}


uint8_t tetris_bucket_rotatePiece(tetris_bucket_t *pBucket,
                                  tetris_piece_rotation_t rotation)
{
	assert(pBucket != NULL);

	// a piece can only be rotation if it is still hovering or gliding
	assert((pBucket->status == TETRIS_BUS_HOVERING) ||
			(pBucket->status == TETRIS_BUS_GLIDING));

	tetris_piece_rotate(pBucket->pPiece, rotation);

	// does the rotated piece cause a collision?
	if (tetris_bucket_collision(pBucket, pBucket->nColumn, pBucket->nRow) != 0)
	{
		// in that case we revert the rotation
		if (rotation == TETRIS_PC_ROT_CW)
		{
			tetris_piece_rotate(pBucket->pPiece, TETRIS_PC_ROT_CCW);
		}
		else
		{
			tetris_piece_rotate(pBucket->pPiece, TETRIS_PC_ROT_CW);
		}

		return 0;
	}

	// are we gliding?
	pBucket->status = tetris_bucket_hoverStatus(pBucket);

	return 1;
}


void tetris_bucket_removeCompleteLines(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);

	// rows can only be removed if we are in state TETRIS_PFS_DOCKED
	assert(pBucket->status == TETRIS_BUS_DOCKED);

	// bit mask of a full row
	uint16_t nFullRow = 0xFFFF >> (16 - pBucket->nWidth);

	// bit mask (only 4 bits) that tells us if the n-th row after the
	// current nRow is complete (n-th bit set to 1, LSB represents nRow itself)
	uint8_t nRowMask = 0;

	// determine sane start and stop values for the dump' index
	int8_t nStartRow = ((pBucket->nRow + 3) >= pBucket->nHeight) ?
			pBucket->nHeight - 1 : pBucket->nRow + 3;
	int8_t nStopRow = (pBucket->nRow < 0) ? 0 : pBucket->nRow;

	// dump index variables
	//   for incomplete rows, both variables will be decremented
	//   for complete rows, only i gets decremented
	int8_t nLowestRow = nStartRow;

	// save old value for the first dump index with matter
	int8_t nFormerFirstMatterRow = pBucket->nFirstMatterRow;

	// this loop only considers rows which are affected by the piece
	for (int8_t i = nStartRow; i >= nStopRow; --i)
	{
		// is current row a full row?
		if ((nFullRow & pBucket->dump[i]) == nFullRow)
		{
			// adjust value for the highest row with matter
			pBucket->nFirstMatterRow++;

			// set corresponding bit for the row mask
			// nRowMask |= 0x08 >> (nStartRow - i);
			nRowMask |= 0x01 <<  (i - pBucket->nRow);
		}
		else
		{
			// if nLowestRow and i differ, the dump has to be shifted
			if (i < nLowestRow)
			{
				pBucket->dump[nLowestRow] = pBucket->dump[i];
			}
			--nLowestRow;
		}
	}

	// if rows have been removed, this loop shifts the rest of the dump
	uint8_t nComplete = nLowestRow - nStopRow + 1;
	if (nComplete > 0)
	{
		for (int8_t i = nStopRow - 1; nLowestRow >= nFormerFirstMatterRow; --i)
		{
			// is the row we are copying from below the upper border?
			if (i >= nFormerFirstMatterRow)
			{
				// just copy from that row
				pBucket->dump[nLowestRow] = pBucket->dump[i];
			}
			else
			{
				// rows above the upper border are always empty
				pBucket->dump[nLowestRow] = 0;
			}
			--nLowestRow;
		}
	}

	// ready to get the next piece
	pBucket->status = TETRIS_BUS_READY;

	pBucket->nRowMask = nRowMask;
}


/*****************
 * get functions *
 *****************/

int8_t tetris_bucket_getWidth(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->nWidth;
}


int8_t tetris_bucket_getHeight(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->nHeight;
}


tetris_piece_t *tetris_bucket_getPiece(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->pPiece;
}


int8_t tetris_bucket_getColumn(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->nColumn;
}


int8_t tetris_bucket_getRow(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->nRow;
}


int8_t tetris_bucket_getFirstMatterRow(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->nFirstMatterRow;
}


uint8_t tetris_bucket_getRowMask(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->nRowMask;
}


tetris_bucket_status_t tetris_bucket_getStatus(tetris_bucket_t *pBucket)
{
	assert(pBucket != NULL);
	return pBucket->status;
}


uint16_t tetris_bucket_getDumpRow(tetris_bucket_t *pBucket,
                                  int8_t nRow)
{
	assert(pBucket != NULL);
	assert((0 <= nRow) && (nRow < pBucket->nHeight));
	return pBucket->dump[nRow];
}


#ifdef GAME_BASTET

int8_t tetris_bucket_predictDeepestRow(tetris_bucket_t *pBucket,
                                       tetris_piece_t *pPiece,
                                       int8_t nColumn)
{
	int8_t nRow = tetris_bucket_getPieceStartPos(pPiece);
	tetris_piece_t *pActualPiece  = pBucket->pPiece;
	pBucket->pPiece = pPiece;

	// is it actually possible to use this piece?
	if (tetris_bucket_collision(pBucket, (pBucket->nWidth - 2) / 2, nRow) ||
			(tetris_bucket_collision(pBucket, nColumn, nRow)))
	{
		// restore real piece
		pBucket->pPiece = pActualPiece;

		return -4;
	}

	// determine deepest row
	nRow = (nRow < pBucket->nFirstMatterRow - 4) ?
			pBucket->nFirstMatterRow - 4 : nRow;
	while ((nRow < pBucket->nHeight) &&
			(!tetris_bucket_collision(pBucket, nColumn, nRow + 1)))
	{
			++nRow;
	}

	// restore real piece
	pBucket->pPiece = pActualPiece;

	return nRow;
}


int8_t tetris_bucket_predictCompleteLines(tetris_bucket_t *pBucket,
                                          tetris_piece_t *pPiece,
                                          int8_t nRow,
                                          int8_t nColumn)
{
	int8_t nCompleteRows = 0;

	// bit mask of a full row
	uint16_t nFullRow = 0xFFFF >> (16 - pBucket->nWidth);

	if (nRow > -4)
	{
		// determine sane start and stop values for the dump's index
		int8_t nStartRow =
			((nRow + 3) >= pBucket->nHeight) ? pBucket->nHeight - 1 : nRow + 3;
		int8_t nStopRow = (nRow < 0) ? 0 : nRow;

		uint16_t nPiece = tetris_piece_getBitmap(pPiece);

		for (int8_t i = nStartRow; i >= nStopRow; --i)
		{
			int8_t y = i - nRow;

			// clear all bits of the piece we are not interested in and
			// align the rest to LSB
			uint16_t nPieceMap = (nPiece & (0x000F << (y << 2))) >> (y << 2);
			// shift the remaining content to the current column
			if (nColumn >= 0)
			{
				nPieceMap <<= nColumn;
			}
			else
			{
				nPieceMap >>= -nColumn;
			}
			// embed piece in dump map
			uint16_t nDumpMap = pBucket->dump[i] | nPieceMap;

			// is current row a full row?
			if ((nFullRow & nDumpMap) == nFullRow)
			{
				++nCompleteRows;
			}
		}
	}

	return nCompleteRows;
}


uint16_t* tetris_bucket_predictBottomRow(tetris_bucket_iterator_t *pIt,
                                         tetris_bucket_t *pBucket,
                                         tetris_piece_t *pPiece,
                                         int8_t nRow,
                                         int8_t nColumn)
{
	pIt->pBucket = pBucket;
	pIt->pPiece = pPiece;
	pIt->nColumn = nColumn;
	pIt->nFullRow = 0xFFFF >> (16 - pBucket->nWidth);
	pIt->nCurrentRow = pBucket->nHeight - 1;
	pIt->nRowBuffer = 0;

	// determine sane start and stop values for the piece's row indices
	pIt->nPieceHighestRow = nRow;
	pIt->nPieceLowestRow = ((pIt->nPieceHighestRow + 3) < pBucket->nHeight) ?
			(pIt->nPieceHighestRow + 3) : pBucket->nHeight - 1;

	// don't return any trailing rows which are empty, so we look for a stop row
	pIt->nStopRow = pBucket->nFirstMatterRow < nRow ?
			pBucket->nFirstMatterRow : nRow;
	pIt->nStopRow = pIt->nStopRow < 0 ? 0 : pIt->nStopRow;

	return tetris_bucket_predictNextRow(pIt);
}


uint16_t* tetris_bucket_predictNextRow(tetris_bucket_iterator_t *pIt)
{
	uint16_t nPieceMap = 0;

	if ((pIt->nPieceHighestRow > -4) && (pIt->nCurrentRow >= pIt->nStopRow))
	{
		uint16_t nPiece = tetris_piece_getBitmap(pIt->pPiece);

		if ((pIt->nCurrentRow <= pIt->nPieceLowestRow) &&
				(pIt->nCurrentRow >= pIt->nPieceHighestRow))
		{
			int8_t y = pIt->nCurrentRow - pIt->nPieceHighestRow;

			// clear all bits of the piece we are not interested in and
			// align the rest to LSB
			nPieceMap = (nPiece & (0x000F << (y << 2))) >> (y << 2);
			// shift the remaining content to the current column
			if (pIt->nColumn >= 0)
			{
				nPieceMap <<= pIt->nColumn;
			}
			else
			{
				nPieceMap >>= -pIt->nColumn;
			}
		}

		pIt->nRowBuffer = pIt->pBucket->dump[pIt->nCurrentRow--] | nPieceMap;
		// don't return full (and therefore removed) rows
		if (pIt->nRowBuffer == pIt->nFullRow)
		{
			// recursively determine next (?) row instead
			return tetris_bucket_predictNextRow(pIt);
		}
		// row isn't full
		else
		{
			return &pIt->nRowBuffer;
		}
	}
	else
	{
		return NULL;
	}
}

#endif /* GAME_BASTET */