Datasheet

Differences

__use_realtime_division()

Selects a helper division routine that always executes in fewer than 45

cycles. Some applications require a faster worst-case cycle count at the

expense of lower average performance.

Headers

C/C++ headers in the

Include

directory provide access to DSP functionality such as

saturating addition and short (16x16 bit) multiplication.

•

armdsp.h

provides functions corresponding exactly to the ARM9E instructions

•

dspfns.h

provides a close approximation to the ITU DSP primitives.

Inline Thumb assembly language

The use of inline Thumb assembly language is deprecated and generates a warning

message. The compiler now generates optimum Thumb code and there is no advantage

to using inline assembly language in Thumb C or C++ code.

Changes to the libraries

The ARM C libraries enable a choice of division helper routines:

• The new integer divide routine in the C library gives known worst-case

performance (less than 45 cycles).

• The default divide routine provides good overall performance, but slower

worst-case performance (more than 90 cycles).

Changes to the size of wchar_t

wchar_t

is now defined to be

unsigned

short

(sizeof(wchar_t) == 2)

. Previously it was

defined as

int

(sizeof(wchar_t) ==4)

__user_initial_stackheap()

has been changed to use the value of the symbol

Image$$ZI$$Limit

instead of

Image$$RW$$Limit

. These symbols have the same value. The

change has been made for the sake of clarity.

2.2.4 Changes to the assembler

This section describes:

• C compiler as preprocessor on page 2-8