596 lines
16 KiB
C
596 lines
16 KiB
C
#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <inttypes.h>
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#include "playfield.h"
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#include "piece.h"
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/***************************
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* non-interface functions *
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***************************/
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/* Function: tetris_playfield_hoverStatus;
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* Description: determines if piece is either hovering or gliding
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* Argument pPl: playfield perform action on
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* Return value: TETRIS_PFS_HOVERING or TETRIS_PFS_GLIDING
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*/
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tetris_playfield_status_t tetris_playfield_hoverStatus(tetris_playfield_t* pPl)
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{
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// if the piece touches the dump we ensure that the status is "gliding"
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if (tetris_playfield_collision(pPl, pPl->nColumn, pPl->nRow + 1))
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{
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return TETRIS_PFS_GLIDING;
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}
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// otherwise the status must be "hovering"
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else
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{
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return TETRIS_PFS_HOVERING;
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}
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}
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/****************************
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* construction/destruction *
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****************************/
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/* Function: tetris_playfield_construct
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* Description: constructs a playfield with the given diemensions
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* Argument nWidth: width of playfield (4 <= n <= 16)
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* Argument nHeight: height of playfield (4 <= n <= 124)
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* Return value: pointer to a newly created playfield
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*/
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tetris_playfield_t *tetris_playfield_construct(int8_t nWidth,
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int8_t nHeight)
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{
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assert((nWidth >= 4) && (nWidth <= 16));
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assert((nHeight >= 4) && (nHeight <= 124));
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tetris_playfield_t *pPlayfield =
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(tetris_playfield_t*) malloc(sizeof(tetris_playfield_t));
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if (pPlayfield != NULL)
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{
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// allocating mem for dump array
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pPlayfield->dump = (uint16_t*) calloc(nHeight, sizeof(uint16_t));
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if (pPlayfield->dump != NULL)
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{
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// setting desired attributes
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pPlayfield->nWidth = nWidth;
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pPlayfield->nHeight = nHeight;
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tetris_playfield_reset(pPlayfield);
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return pPlayfield;
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}
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else
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{
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free(pPlayfield);
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pPlayfield = NULL;
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}
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}
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return NULL;
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}
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/* Function: tetris_playfield_destruct
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* Description: destructs a playfield
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* Argument pPl: pointer to the playfield to be destructed
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* Return value: void
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*/
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void tetris_playfield_destruct(tetris_playfield_t *pPl)
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{
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assert(pPl != NULL);
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// if memory for the dump array has been allocated, free it
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if (pPl->dump != NULL)
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{
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free(pPl->dump);
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}
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free(pPl);
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}
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/*******************************
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* playfield related functions *
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*******************************/
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/* Function: tetris_playfield_reset
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* Description: resets playfield to begin a new game
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* Argument pPl: playfield to perform action on
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* Return value: void
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*/
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void tetris_playfield_reset(tetris_playfield_t *pPl)
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{
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assert(pPl != NULL);
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pPl->pPiece = NULL;
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pPl->nColumn = 0;
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pPl->nRow = 0;
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pPl->nRowMask = 0;
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// clear dump if it has been allocated in memory
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if (pPl->dump != NULL)
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{
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memset(pPl->dump, 0, pPl->nHeight);
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}
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pPl->status = TETRIS_PFS_READY;
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}
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/* Function: tetris_playfield_insertPiece
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* Description: inserts a new piece
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* Argument pPl: playfield to perform action on
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* Argument pPiece: piece to be inserted
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* Argument ppOldPiece: [out] indirect pointer to former piece for deallocation
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* Return value: void
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*/
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void tetris_playfield_insertPiece(tetris_playfield_t *pPl,
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tetris_piece_t *pPiece,
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tetris_piece_t** ppOldPiece)
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{
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assert((pPl != NULL) && (pPiece != NULL) && (ppOldPiece != NULL));
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// a piece can only be inserted in state TETRIS_PFS_READY
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assert(pPl->status == TETRIS_PFS_READY);
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// row mask is now meaningless
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pPl->nRowMask = 0;
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// replace old piece
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*ppOldPiece = pPl->pPiece;
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pPl->pPiece = pPiece;
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// set horizontal start position (in the middle of the top line)
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pPl->nColumn = (pPl->nWidth - 2) / 2;
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// set vertical start position (first piece row with matter at pos. 1)
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uint16_t nPieceMap = tetris_piece_getBitmap(pPl->pPiece);
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uint16_t nElementMask = 0xF000;
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pPl->nRow = -3;
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while ((nPieceMap & nElementMask) == 0)
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{
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++pPl->nRow;
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nElementMask >>= 4;
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}
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if (pPl->nRow < 0)
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{
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++pPl->nRow;
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}
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// did we already collide with something?
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if (tetris_playfield_collision(pPl, pPl->nColumn, pPl->nRow) == 1)
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{
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// game over man, game over!!
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pPl->status = TETRIS_PFS_GAMEOVER;
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}
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else
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{
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// bring it on!
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pPl->status = tetris_playfield_hoverStatus(pPl);
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}
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}
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/* Function: tetris_playfield_collision
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* Description: detects if piece collides with s.th. at a given position
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* Argument pPl: playfield to perform action on
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* Argument nColumn: column where the piece should be moved
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* Argument nRow: row where the piece should be moved
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* Return value: 1 for collision, 0 otherwise
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*/
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uint8_t tetris_playfield_collision(tetris_playfield_t *pPl,
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int8_t nColumn,
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int8_t nRow)
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{
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assert(pPl != NULL);
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// only allow coordinates which are within sane ranges
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assert((nColumn >= -4) && (nColumn < pPl->nWidth));
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assert((nRow >= -4) && (nRow < pPl->nHeight));
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// The rows of a piece get compared with the background one by one
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// until either a collision occures or all rows are compared. Both the
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// piece row and the part of the playfield it covers are represented in
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// 4 bits which were singled out from their corresponding uint16_t
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// values and are aligned to LSB. In case where a piece overlaps with
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// either the left or the right border we "enhance" the playfield part
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// via bit shifting and set all bits representing the border to 1.
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//
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// NOTE: LSB represents the left most position.
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uint16_t nPieceMap = tetris_piece_getBitmap(pPl->pPiece);
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uint16_t nPlayfieldPart;
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uint16_t nPieceRowMap;
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// negative nRow values indicate that the piece hasn't fully entered the
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// playfield yet which requires special treatment if the piece overlaps
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// with either the left or the right border
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if (nRow < 0)
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{
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uint16_t nBorderMask = 0x0000;
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// piece overlaps with left border
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if (nColumn < 0)
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{
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nBorderMask = 0x1111 << (-nColumn - 1);
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}
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// piece overlaps with right border
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else if ((nColumn + 3) >= pPl->nWidth)
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{
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nBorderMask = 0x8888 >> ((nColumn + 3) - pPl->nWidth);
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}
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// return if piece collides with border
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if ((nPieceMap & nBorderMask) != 0)
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{
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return 1;
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}
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}
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// here we check the part which has already entered the playfield
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for (int8_t y = (nRow < 0) ? -nRow : 0; y < 4; ++y)
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{
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// current piece row overlaps with lower border
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if ((y + nRow) >= pPl->nHeight)
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{
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// all 4 bits represent the lower border
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nPlayfieldPart = 0x000F;
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}
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// piece overlaps with left border
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else if (nColumn < 0)
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{
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// clear all bits we are not interested in
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nPlayfieldPart = (pPl->dump[y + nRow] & (0x000F >> -nColumn));
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// add zeros to the left (the bits "behind" the left border)
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nPlayfieldPart <<= -nColumn;
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// set bits beyond left border to 1
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nPlayfieldPart |= 0x000F >> (4 + nColumn);
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}
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// piece overlaps with right border
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else if ((nColumn + 3) >= pPl->nWidth)
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{
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// align the bits we are interested in to LSB
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// (thereby clearing the rest)
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nPlayfieldPart = pPl->dump[y + nRow] >> nColumn;
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// set bits beyond right border to 1
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nPlayfieldPart |= 0xFFF8 >> (nColumn + 3 - pPl->nWidth);
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}
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// current row neither overlaps with left, right nor lower border
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else
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{
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// clear all bits we are not interested in and align the
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// remaing row to LSB
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nPlayfieldPart =
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(pPl->dump[y + nRow] & (0x000F << nColumn)) >> nColumn;
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}
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// clear all bits of the piece we are not interested in and
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// align the remaing row to LSB
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nPieceRowMap = (nPieceMap & (0x000F << (y << 2))) >> (y << 2);
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// finally check for a collision
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if ((nPlayfieldPart & nPieceRowMap) != 0)
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{
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return 1;
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}
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}
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// if we reach here, no collision was detected
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return 0;
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}
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/* Function: tetris_playfield_advancePiece
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* Description: lowers piece by one row or finally docks it
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* Argument pPl: playfield to perform action on
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* Return value: void
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*/
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void tetris_playfield_advancePiece(tetris_playfield_t *pPl)
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{
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assert(pPl != NULL);
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// a piece can only be lowered if it is hovering or gliding
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assert ((pPl->status == TETRIS_PFS_HOVERING) ||
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(pPl->status == TETRIS_PFS_GLIDING));
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if (tetris_playfield_collision(pPl, pPl->nColumn, pPl->nRow + 1))
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{
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uint16_t nPiece = tetris_piece_getBitmap(pPl->pPiece);
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// Is the playfield filled up?
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if ((pPl->nRow < 0) && (nPiece & (0x0FFF >> ((3 + pPl->nRow) << 2))) != 0)
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{
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pPl->status = TETRIS_PFS_GAMEOVER;
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}
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else
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{
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// determine valid start point for dump index
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int8_t nStartRow = ((pPl->nRow + 3) < pPl->nHeight) ?
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(pPl->nRow + 3) : pPl->nHeight - 1;
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for (int8_t i = nStartRow; i >= pPl->nRow; --i)
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{
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int8_t y = i - pPl->nRow;
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// clear all bits of the piece we are not interested in and
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// align the rest to LSB
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uint16_t nPieceMap = (nPiece & (0x000F << (y << 2))) >> (y << 2);
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// shift the remaining content to the current column
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if (pPl->nColumn >= 0)
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{
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nPieceMap <<= pPl->nColumn;
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}
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else
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{
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nPieceMap >>= -pPl->nColumn;
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}
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// embed piece in playfield
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pPl->dump[i] |= nPieceMap;
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}
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// the piece has finally been docked
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pPl->status = TETRIS_PFS_DOCKED;
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}
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}
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else
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{
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// since there is no collision the piece may continue its travel
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// to the ground...
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pPl->nRow++;
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// are we gliding?
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pPl->status = tetris_playfield_hoverStatus(pPl);
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}
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}
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/* Function: tetris_playfield_movePiece
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* Description: moves piece to the given direction
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* Argument pPl: playfield to perform action on
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* Argument direction: direction (see tetris_playfield_direction_t)
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* Return value: 1 if piece could be moved, 0 otherwise
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*/
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uint8_t tetris_playfield_movePiece(tetris_playfield_t *pPl,
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tetris_playfield_direction_t direction)
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{
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assert(pPl != NULL);
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// a piece can only be moved if it is still hovering or gliding
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assert((pPl->status == TETRIS_PFS_HOVERING) ||
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(pPl->status == TETRIS_PFS_GLIDING));
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int8_t nOffset = (direction == TETRIS_PFD_LEFT) ? -1 : 1;
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if (tetris_playfield_collision(pPl, pPl->nColumn + nOffset, pPl->nRow) == 0)
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{
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pPl->nColumn += nOffset;
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// are we gliding?
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pPl->status = tetris_playfield_hoverStatus(pPl);
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return 1;
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}
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return 0;
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}
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/* Function: tetris_playfield_rotatePiece
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* Description: rotates piece to the given direction
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* Argument pPl: playfield to perform action on
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* Argument r: type of rotation (see tetris_piece_rotation_t)
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* Return value: 1 if piece could be rotated, 0 otherwise
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*/
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uint8_t tetris_playfield_rotatePiece(tetris_playfield_t *pPl,
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tetris_piece_rotation_t rotation)
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{
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assert(pPl != NULL);
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// a piece can only be rotation if it is still hovering or gliding
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assert((pPl->status == TETRIS_PFS_HOVERING) ||
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(pPl->status == TETRIS_PFS_GLIDING));
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tetris_piece_rotate(pPl->pPiece, rotation);
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// does the rotated piece cause a collision?
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if (tetris_playfield_collision(pPl, pPl->nColumn, pPl->nRow) != 0)
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{
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// in that case we revert the rotation
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if (rotation == TETRIS_PC_ROT_CW)
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{
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tetris_piece_rotate(pPl->pPiece, TETRIS_PC_ROT_CCW);
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}
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else
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{
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tetris_piece_rotate(pPl->pPiece, TETRIS_PC_ROT_CW);
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}
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return 0;
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}
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// are we gliding?
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pPl->status = tetris_playfield_hoverStatus(pPl);
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return 1;
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}
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/* Function: tetris_playfield_removeCompletedLines
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* Description: removes completed lines (if any) and lowers the dump
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* Argument pPl: playfield to perform action on
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* Return value: void
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*/
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void tetris_playfield_removeCompleteLines(tetris_playfield_t *pPl)
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{
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assert(pPl != NULL);
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// rows can only be removed if we are in state TETRIS_PFS_DOCKED
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assert(pPl->status == TETRIS_PFS_DOCKED);
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// bit mask of a full row
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uint16_t nFullRow = 0xFFFF >> (16 - pPl->nWidth);
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// bit mask (only 4 bits) that tells us if the n-th row after the
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// current nRow is complete (n-th bit set to 1, LSB represents nRow itself)
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uint8_t nRowMask = 0;
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// determine sane start and stop values for the dump' index
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int8_t nStartRow =
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((pPl->nRow + 3) >= pPl->nHeight) ? pPl->nHeight - 1 : pPl->nRow + 3;
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int8_t nStopRow = (pPl->nRow < 0) ? 0 : pPl->nRow;
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// dump index variables
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// for incomplete rows, both variables will be decremented
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// for complete rows, only i gets decremented
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int8_t nLowestRow = nStartRow;
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// this loop only considers rows which are affected by the piece
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for (int8_t i = nStartRow; i >= nStopRow; --i)
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{
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// is current row a full row?
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if ((nFullRow & pPl->dump[i]) == nFullRow)
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{
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// set corresponding bit for the row mask
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// nRowMask |= 0x08 >> (nStartRow - i);
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nRowMask |= 0x01 << (i - pPl->nRow);
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}
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else
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{
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// if nLowestRow and i differ, the dump has to be shifted
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if (i < nLowestRow)
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{
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pPl->dump[nLowestRow] = pPl->dump[i];
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}
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--nLowestRow;
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}
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}
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// if rows have been removed, this loop shifts the rest of the dump
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uint8_t nComplete = nLowestRow - nStopRow + 1;
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if (nComplete > 0)
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{
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for (int8_t i = nStopRow - 1; nLowestRow >= 0; --i)
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{
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// is the row we are copying from below the upper border?
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if (i >= 0)
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{
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// just copy from that row
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pPl->dump[nLowestRow] = pPl->dump[i];
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}
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else
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{
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// rows above the upper border are always empty
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pPl->dump[nLowestRow] = 0;
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}
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--nLowestRow;
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}
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}
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// ready to get the next piece
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pPl->status = TETRIS_PFS_READY;
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pPl->nRowMask = nRowMask;
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}
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/*****************
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* get functions *
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*****************/
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/* Function: tetris_playfield_getWidth
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* Description: returns the width of the playfield
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* Argument pPl: the playfield we want information from
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* Return value: width of the playfield
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*/
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int8_t tetris_playfield_getWidth(tetris_playfield_t *pPl)
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{
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assert(pPl != NULL);
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return pPl->nWidth;
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}
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/* Function: tetris_playfield_getHeight
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* Description: returns the height of the playfield
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* Argument pPl: the playfield we want information from
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* Return value: height of the playfield
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*/
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int8_t tetris_playfield_getHeight(tetris_playfield_t *pPl)
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{
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assert(pPl != NULL);
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return pPl->nHeight;
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}
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/* Function: tetris_playfield_getPiece
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* Description: returns the currently falling piece
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* Argument pPl: the playfield we want information from
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* Return value: pointer to the currently falling piece
|
|
*/
|
|
tetris_piece_t *tetris_playfield_getPiece(tetris_playfield_t *pPl)
|
|
{
|
|
assert(pPl != NULL);
|
|
return pPl->pPiece;
|
|
}
|
|
|
|
|
|
/* Function: tetris_playfield_getColumn
|
|
* Description: returns the column of the currently falling piece
|
|
* Argument pPl: the playfield we want information from
|
|
* Return value: column of the currently falling piece
|
|
*/
|
|
int8_t tetris_playfield_getColumn(tetris_playfield_t *pPl)
|
|
{
|
|
assert(pPl != NULL);
|
|
return pPl->nColumn;
|
|
}
|
|
|
|
|
|
/* Function: tetris_playfield_getRow
|
|
* Description: returns the row of the currently falling piece
|
|
* Argument pPl: the playfield we want information from
|
|
* Return value: row of the currently falling piece
|
|
*/
|
|
int8_t tetris_playfield_getRow(tetris_playfield_t *pPl)
|
|
{
|
|
assert(pPl != NULL);
|
|
return pPl->nRow;
|
|
}
|
|
|
|
|
|
/* Function: tetris_playfield_getRowMask
|
|
* Description: returns the row mask relative to nRow
|
|
* Argument pPl: the playfield we want information from
|
|
* Return value: the first 4 bits indicate which lines (relative to nRow)
|
|
* have been removed if we are in status TETRIS_PFS_READY
|
|
* LSB is the highest line
|
|
*/
|
|
uint8_t tetris_playfield_getRowMask(tetris_playfield_t *pPl)
|
|
{
|
|
assert(pPl != NULL);
|
|
return pPl->nRowMask;
|
|
}
|
|
|
|
|
|
/* Function: tetris_playfield_getStatus
|
|
* Description: returns the status of the playfield
|
|
* Argument pPl: the playfield we want information from
|
|
* Return value: status of the playfield (see tetris_playfield_status_t)
|
|
*/
|
|
tetris_playfield_status_t tetris_playfield_getStatus(tetris_playfield_t *pPl)
|
|
{
|
|
assert(pPl != NULL);
|
|
return pPl->status;
|
|
}
|
|
|
|
|
|
/* Function: tetris_playfield_getDumpRow
|
|
* Description: returns the given row of the dump (as bitmap)
|
|
* Argument pPl: the playfield we want information from
|
|
* Argument nRow: the number of the row (0 <= nRow < height of playfield)
|
|
* Return value: bitmap of the requested row (LSB is leftmost column)
|
|
*/
|
|
uint16_t tetris_playfield_getDumpRow(tetris_playfield_t *pPl,
|
|
int8_t nRow)
|
|
{
|
|
assert(pPl != NULL);
|
|
assert((0 <= nRow) && (nRow < pPl->nHeight));
|
|
return pPl->dump[nRow];
|
|
}
|
|
|