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/*
bug-3322.c
A z80 code generation (overwriting a value in iy during an assignment) bug found by z88dk
*/
#include <testfwk.h>
#define PIECE_IS_NEXT 255
#define STARTBOARD_X 15
#define STARTBOARD_Y 2
#define POS_NEXT_X 3
#define POS_NEXT_Y 1
#define NEXT_X (POS_NEXT_X+2)
#define NEXT_Y (POS_NEXT_Y+3)
#define EMPTY_GR_CHAR 32
#define EMPTY_GR_COLOR 0
#define FONTS 0
typedef unsigned char byte;
// tetromino sprite
typedef struct {
int x; // signed integers to allow negative board positions
int y; // -1 means piece is preview ("next")
byte piece;
byte angle;
} sprite;
#define gr4_tile(x,y,tile,color,tileset) _gr4_tile_x = (x); _gr4_tile_y = (y); _gr4_tile_tile = (tile); _gr4_tile_color = (color); _gr4_tile_tileset = (tileset); _gr4_tile()
byte _gr4_tile_x;
byte _gr4_tile_y;
byte _gr4_tile_tile;
byte _gr4_tile_color;
byte *_gr4_tile_tileset;
byte *_gr4_tile_source;
byte *_gr4_tile_dest;
void _gr4_tile() {
}
// offset of a single tile composing a piece
typedef struct {
byte offset_x;
byte offset_y;
} tile_offset;
tile_offset *get_piece_offsets(byte piece, byte angle);
tile_offset pieces_XY[4] = {
{+1,+1} , {+2,+1} , {+3,+1} , {+1,+2} ,
};
void SLOT1_VIDEO_START() {
}
void SLOT1_END() {
}
// given a piece number and an angle returns the 4 byte "offsets" of the piece
tile_offset *get_piece_offsets(byte piece, byte angle) {
return &pieces_XY[(piece*sizeof(tile_offset)*4*2)+angle*4];
}
void gr_erasepiece(sprite *p);
// erase piece from the screen
void gr_erasepiece(sprite *p) {
tile_offset *data = get_piece_offsets(p->piece, p->angle); // bug if this declaration is here
int px = p->x;
int py = p->y;
// are we erasing the "next" piece ?
if(py==PIECE_IS_NEXT) {
px = NEXT_X;
py = NEXT_Y;
}
else {
px += STARTBOARD_X;
py += STARTBOARD_Y;
}
// tile_offset *data = get_piece_offsets(p->piece, p->angle); // no bug if this declaration is here
SLOT1_VIDEO_START();
for(byte t=0; t<4; t++) {
int x = px + data->offset_x;
int y = py + data->offset_y;
data++;
gr4_tile((byte)x,(byte)y,EMPTY_GR_CHAR,EMPTY_GR_COLOR,FONTS);
}
SLOT1_END();
}
void testBug(void)
{
sprite s;
s.x = 0;
s.y = 0;
s.piece = 0;
s.angle = 0;
gr_erasepiece(&s);
ASSERT(_gr4_tile_x == s.x + STARTBOARD_X + pieces_XY[3].offset_x);
ASSERT(_gr4_tile_y == s.y + STARTBOARD_Y + pieces_XY[3].offset_y);
}
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