SW006015 Microchip Technology, SW006015 Datasheet - Page 62

• Manufacturer Part Number: SW006015
• Description: C COMPILER MPLAB C32
• Manufacturer: Microchip Technology
• Type: Compilerr
• Series: PIC32r

Specifications of SW006015

• Supported Families: PIC32MX5, MX6, And MX7
• Core Architecture: PIC
• Kit Contents: Software And Docs
• Mcu Supported Families: PIC32 MCUs
• Tool Function: Compiler
• Supported Devices: PIC32 MCUs
• Tool Type: Compiler
• Processor Series: PIC32
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• For Use With/related Products: PIC32
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

5.4
DS51686A-page 58
STACK USAGE
®
The MPLAB C32 C compiler dedicates general purpose register 29 as the software
Stack Pointer. All processor stack operations, including function call, interrupts and
exceptions use the software stack. The stack grows downward from high addresses to
low addresses.
By default, the size of the stack is 1024 bytes. The size of the stack may be changed
by specifying the size on the linker command line using the
--defsym_min_stack_size linker command line option. An example of allocating
a stack of 2048 bytes using the command line is:
pic32-gcc foo.c -Wl,--defsym,_min_stack_size=2048
The runtime stack grows downward from higher addresses to lower addresses (see
Figure 5-1). The compiler uses two working registers to manage the stack:
• Register 29 (sp) – This is the Stack Pointer. It points to the next free location on
• Register 30 (fp) – This is the Frame Pointer. It points to the current function’s
FIGURE 5-1:
the stack.
frame. Each function, if required, creates a new frame from which automatic and
temporary variables are allocated. Compiler optimization may eliminate Stack
Pointer references via the Frame Pointer to equivalent references via the Stack
Pointer. This optimization allows the Frame Pointer to be used as a general
purpose register.
STACK FRAME
Caller
FP
Callee
SP
Space for more
arguments if
necessary
Space for argument 4
Space for argument 3
Space for argument 2
Space for argument 1
Local variables and
temporary values
Register save area
Space for arguments
used in function calls
© 2007 Microchip Technology Inc.
Stack grows
toward
lower
addresses