Analog Devices EE-62 Accessing Short Word Memory in C Application Note

About this manual

The document provides technical guidance on accessing short word (16-bit) memory in C for the Analog Devices ADSP-2106x SHARC family of DSP components. While the C runtime environment natively processes 32-bit data, this note details how to manually place variables into specific 16-bit memory segments to improve efficiency and data granularity.

It covers two primary development tool versions: VisualDSP (using the 'segment' qualifier in linker description files) and v3.3 tools (requiring separate compilation with the '-mpmdata=' compiler switch). The text includes examples of Linker Description File (LDF) configurations, architecture file settings, and C source code snippets demonstrating variable placement.

What's inside

• Introduction
• VisualDSP Development Tools Example
• Setting Up Your LDF
• V3.3 Family Development Tools Example
• Manipulating Signed 16-bit Data

Frequently asked questions

What is the purpose of this application note?

This note explains how to place variables and other datatypes into 16-bit, or short-word memory, to allow for a more efficient use of memory.

What is the memory address range for the alt_dmda segment?

The alt_dmda segment starts at address 0x0007c000 and ends at address 0x0007ffff.

What compiler switch is used to place code in an alternate segment for v3.3 tools?

You must use the -mpmdata= compiler switch to place the source file in the desired segment.