MPLAB C Compiler for PIC24 MCUs and dsPIC DSCs ... - Microchip

4.1 INTRODUCTION
4.2 HIGHLIGHTS
4.3 ADDRESS SPACES
MPLAB ® C COMPILER FOR
PIC24 MCUs AND dsPIC ® DSCs
USER’S GUIDE
Chapter 4. Run Time Environment
This section discusses the MPLAB C Compiler for PIC24 MCUs and dsPIC ® DSCs
(formerly MPLAB C30) run-time environment.
Items discussed in this chapter are:
• Address Spaces
• Startup and Initialization
• Memory Spaces
• Memory Models
• Locating Code and Data
• Software Stack
• The C Stack Usage
• The C Heap Usage
• Function Call Conventions
• Register Conventions
• Bit Reversed and Modulo Addressing
• Program Space Visibility (PSV) Usage
The dsPIC Digital Signal Controller (DSC) devices are a combination of traditional PIC ®
Microcontroller (MCU) features (peripherals, Harvard architecture, RISC) and new
DSP capabilities. The dsPIC DSC devices have two distinct memory regions:
• Program Memory contains executable code and optionally constant data.
• Data Memory contains external variables, static variables, the system stack and
file registers. Data memory consists of near data, which is memory in the first 8
KB of the data memory space, and far data, which is in the upper 56 KB of data
memory space.
Although the program and data memory regions are distinctly separate, the compiler
can access constant data in program memory through the program space visibility
window.
© 2008 Microchip Technology Inc. DS51284H-page 63