wordclock/games/tetris/piece.c

#include <stdlib.h>
#include <assert.h>
#include <inttypes.h>
#include "piece.h"

#ifdef __AVR__
	#include <avr/pgmspace.h>
#else
	#define PROGMEM
#endif


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

/* Function:     tetris_piece_construct
 * Description:  constructs a piece with the given attributes
 * Argument s:   shape of the piece (see tetris_piece_shape_t)
 * Argument a:   its angle (see tetris_piece_angel_t)
 * Return value: pointer to a newly created piece
 */
tetris_piece_t *tetris_piece_construct(tetris_piece_shape_t s,
                                       tetris_piece_angle_t a)
{
	tetris_piece_t *p_piece = (tetris_piece_t*) malloc (sizeof(tetris_piece_t));
	assert(p_piece != NULL);

	p_piece->shape = s;
	p_piece->angle = a;

	return p_piece;
}

/* Function:     tetris_piece_destruct
 * Description:  destructs a piece
 * Argument pPc: pointer to the piece to be destructed
 * Return value: void
 */
void tetris_piece_destruct(tetris_piece_t *pPc)
{
	assert(pPc != NULL);
	free(pPc);
}


/****************************
 *  piece related functions *
 ****************************/

/* Function:     tetris_piece_getBitmap
 * Description:  returns bitfield representation of the piece 
 * Argument pPc: piece from which the bitfield shuld be retrieved
 * Return value: bitfield representation of the piece
 *               - nth nibble is nth row of the piece (from upper left)
 *               - the LSB of a nibble represents the left side of a row
 */
uint16_t tetris_piece_getBitmap(tetris_piece_t *pPc)
{
	assert(pPc != NULL);

	// Lookup table:
	// A value in an array represents a piece in a specific angle (rotating
	// clockwise from index 0).
	const static uint16_t piece[][4] PROGMEM =
		{{0x0F00, 0x2222, 0x0F00, 0x2222},  // LINE
		 {0x4E00, 0x4640, 0x0E40, 0x4C40},  // T
		 {0x0660, 0x0660, 0x0660, 0x0660},  // SQUARE
		 {0x2E00, 0x88C0, 0x0E80, 0xC440},  // L
		 {0x8E00, 0x6440, 0x0E20, 0x44C0},  // LBACK
		 {0x6C00, 0x4620, 0x6C00, 0x4620},  // S
		 {0xC600, 0x4C80, 0xC600, 0x4C80}}; // Z

	#ifdef __AVR__
		return pgm_read_word(&piece[pPc->shape][pPc->angle]);
	#else
		return piece[pPc->shape][pPc->angle];
	#endif
}


/* Function:     tetris_piece_rotate
 * Description:  rotates a piece
 * Argument pPc: piece to rotate
 * Argument r:   type of rotation (see tetris_piece_rotation_t)
 * Return value: void
 */
void tetris_piece_rotate(tetris_piece_t *pPc,
                         tetris_piece_rotation_t r)
{
	assert(pPc != NULL);

	// we just rotate through the available angles in the given direction and
	// make wrap arounds where appropriate
	switch (r)
	{
	case TETRIS_PC_ROT_CW:
		if (pPc->angle == TETRIS_PC_ANGLE_270)
		{
			pPc->angle = TETRIS_PC_ANGLE_0;
		}
		else
		{
			++pPc->angle;
		}
		break;
	case TETRIS_PC_ROT_CCW:
		if (pPc->angle == TETRIS_PC_ANGLE_0)
		{
			pPc->angle = TETRIS_PC_ANGLE_270;
		}
		else
		{
			--pPc->angle;
		}
		break;
	}
}