Z80 Assembly 91: Fast 16-bit Block Clear (memset to Zero)
The Need for a Fast Block Clear Initializing memory to zero is one of the most common tasks in low-level programming (the equivalent of calling memset(ptr, 0, size) in C). Since the Z80 needs to clear large buffers, a highly optimized routine is essential. Goal: Fill a specified memory range (START_ADDR′ to END_ADDR′) with the byte value `00H′ as quickly as possible. The Optimized Strategy: Using LDIR The fastest method is a slight modification of the Block Fill routine (Part 85), exploiting the `LDIR′ (Load, Increment, Repeat) instruction. ...