MSC100ABIRM Motorola / Freescale Semiconductor, MSC100ABIRM Datasheet - Page 26

• Manufacturer Part Number: MSC100ABIRM
• Description: SC100 Application Binary Interface Reference Manual
• Manufacturer: Motorola / Freescale Semiconductor

Low-Level Binary Interface
2.3.7 Dynamic Memory Allocation
Dynamic allocations are implemented using a heap structure managed by the standard library functions
malloc() and free(). The heap shall be allocated statically by the linker. In typical configurations, the stack
is allocated above (higher addresses) the static and global variables, growing towards higher addresses.
The heap is allocated at the top of the available memory, growing towards lower memory addresses.
2.3.8 Hardware Loops
All hardware loop resources are available for the compiler’s use. As it is assumed that no nesting occurs
when entering a function, a function may use all four nesting levels for its own use. An additional side
effect of this assumption is that loops with a function call as part of the loop code cannot be implemented
using hardware loops. A compilation switch will be available to disable the use of loop 3. As in interrupts,
this will enable the user to allocate this loop counter to a different execution thread.
Loops will be nested beginning loop counter 0 in the outermost nesting level.
2.3.9 Operating Modes
Compilers should make two assumptions about run-time operating modes and machine state:
2-8
1. All M registers (m0–m3) should be assumed to contain the value -1 (linear addressing).
2. No particular operating mode settings in the OMR register are assumed. It is expected that
Should the use of an M register be required, the using function must restore the M register to
the value -1 before returning or before calling another function.
the user will set the default settings in the start-up code (saturation modes, rounding mode,
and scale bits). These operating modes may change during the application execution under
user control.
Preliminary (April 2000)
SC100 Application Binary Interface