Page 265 - Embedded Microprocessor Systems Real World Design
P. 265
A B
BLOCK SIZE TOO SMALL BLOCK SIZE TOO LARGE
MEMORY BEFORE ALLOCATION MEMORY BEFORE ALLOCATION
BLOCK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
FRAGMENTED MEMORY
BLOCK ALLOCATION ALLOCATION
1
2 TASK 1
3 TASK 1
4 TASK 2
5
6 TASK 2
7 TASK 2
8
9 TASK 3
10 TASK 3
11 TASK 3 TASK 3
12 TASK 3
13
14 TASK 4 TASK 4
15 TASK 4
16
=FREE
-1 - ALLOCATED (UNAVAILABLE)
Figure 9.4
RTOS Memory Allocation Blocks.
output task, the diagnostic task must wait until the interface is released by the
output code.
In the area of timers, the RTOS may provide system timers, implemented in
software and counting timer ticks, that can be allocated like any other resource.
These timers, of course, cannot time anything with a resolution less than the timer
tick interval.
246 Embedded Micropocessm Systems
