ARM Compiler toolchain v4.1 for µVision Using the Compiler

Compiler Features
4.10 Compiler support for European Telecommunications Standards Institute (ETSI)
basic operations
ARM Compiler 4.1 and later provide support for the ETSI basic operations through the header
file dspfns.h. The dspfns.h header file contains definitions of the ETSI basic operations as a
combination of C code and intrinsics.
See dspfns.h for a complete list of the ETSI basic operations supported in ARM Compiler 4.1
and later.
ARM Compiler 4.1 and later support the original ETSI family of basic operations as described
in the ETSI G.729 recommendation Coding of speech at 8 kbit/s using conjugate-structure
algebraic-code-excited linear prediction (CS-ACELP), including:
• 16-bit and 32-bit saturated arithmetic operations, such as add and sub. For example,
add(v1, v2) adds two 16-bit numbers v1 and v2 together, with overflow control and
saturation, returning a 16-bit result.
• 16-bit and 32-bit multiplication operations, such as mult and L_mult. For example,
mult(v1, v2) multiplies two 16-bit numbers v1 and v2 together, returning a scaled 16-bit
result.
• 16-bit arithmetic shift operations, such as shl and shr. For example, the saturating left
shift operation shl(v1, v2) arithmetically shifts the 16-bit input v1 left v2 positions. A
negative shift count shifts v1 right v2 positions.
• 16-bit data conversion operations, such as extract_l, extract_h, and round. For example,
round(L_v1) rounds the lower 16 bits of the 32-bit input L_v1 into the most significant 16
bits with saturation.
Note
Beware that both the dspfns.h header file and the ISO C99 header file math.h both define
(different versions of) the function round(). Take care to avoid this potential conflict.
4.10.1 See also
Concepts
• European Telecommunications Standards Institute (ETSI) basic operations on page 4-12.
Reference
Compiler Reference:
• ETSI basic operations on page 5-89.
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