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Power Programmierung
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Power-Programmierung (Tewi)(1994).iso
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pctchnqs
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1992
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number2
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l4.cpp
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1992-03-21
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/* next_generation(), implemented using fast, all-in-one hard-wired
neighbor count/update/draw function. Otherwise, the same as
Listing 3. */
/* Calculates the next generation of current_map and stores it in
next_map. */
void cellmap::next_generation(cellmap& next_map)
{
unsigned int x, y, neighbor_count;
unsigned int width_in_bytesX2 = width_in_bytes << 1;
unsigned char *cell_ptr, *current_cell_ptr, mask, current_mask;
unsigned char *base_cell_ptr, *row_cell_ptr, base_mask;
unsigned char *dest_cell_ptr = next_map.cells;
// Process all cells in the current cellmap
row_cell_ptr = cells; // point to upper left neighbor of
// first cell in cell map
for (y=0; y<height; y++) { // repeat for each row of cells
// Cell pointer and cell bit mask for first cell in row
base_cell_ptr = row_cell_ptr; // to access upper left neighbor
base_mask = 0x01; // of first cell in row
for (x=0; x<width; x++) { // repeat for each cell in row
// First, count neighbors
// Point to upper left neighbor of current cell
cell_ptr = base_cell_ptr; // pointer and bit mask for
mask = base_mask; // upper left neighbor
// Count upper left neighbor
neighbor_count = (*cell_ptr & mask) ? 1 : 0;
// Count left neighbor
if ((*(cell_ptr + width_in_bytes) & mask)) neighbor_count++;
// Count lower left neighbor
if ((*(cell_ptr + width_in_bytesX2) & mask))
neighbor_count++;
// Point to upper neighbor
if ((mask >>= 1) == 0) {
mask = 0x80;
cell_ptr++;
}
// Remember where to find the current cell
current_cell_ptr = cell_ptr + width_in_bytes;
current_mask = mask;
// Count upper neighbor
if ((*cell_ptr & mask)) neighbor_count++;
// Count lower neighbor
if ((*(cell_ptr + width_in_bytesX2) & mask))
neighbor_count++;
// Point to upper right neighbor
if ((mask >>= 1) == 0) {
mask = 0x80;
cell_ptr++;
}
// Count upper right neighbor
if ((*cell_ptr & mask)) neighbor_count++;
// Count right neighbor
if ((*(cell_ptr + width_in_bytes) & mask)) neighbor_count++;
// Count lower right neighbor
if ((*(cell_ptr + width_in_bytesX2) & mask))
neighbor_count++;
if (*current_cell_ptr & current_mask) {
if ((neighbor_count != 2) && (neighbor_count != 3)) {
*(dest_cell_ptr + (current_cell_ptr - cells)) &=
~current_mask; // turn off cell
draw_pixel(x, y, OFF_COLOR);
}
} else {
if (neighbor_count == 3) {
*(dest_cell_ptr + (current_cell_ptr - cells)) |=
current_mask; // turn on cell
draw_pixel(x, y, ON_COLOR);
}
}
// Advance to the next cell on row
if ((base_mask >>= 1) == 0) {
base_mask = 0x80;
base_cell_ptr++; // advance to the next cell byte
}
}
row_cell_ptr += width_in_bytes; // point to start of next row
}
}