Dual Memory Support Keywords (Pm Dm) - Analog Devices VISUALDSP++ 3.5 Manual

C/C++ Compiler Language Extensions

Dual Memory Support Keywords (pm dm)

This section describes
port the dual-memory space, modified Harvard architecture of the
ADSP-219x processors. There are two keywords used to designate mem-
ory space: and
dm
a static or global variable or to qualify a pointer declaration.
These keywords allow you to control placement of data in primary (
secondary ( ) data memory. No data is placed in the memory unit that
pm
holds programs. The following rules apply to dual memory support
keywords:
• A memory space keyword (
right.
• You can specify a memory space for each level of pointer. This cor-
responds to one memory space for each
• The compiler uses Data Memory as the default memory space for
all variables. All undeclared spaces for data are Data Memory
spaces.
• The compiler always uses Program Memory as the memory space
for functions. Function pointers always point to Program Memory.
• You cannot assign memory spaces to automatic variables. All auto-
matic variables reside on the stack, which is always in Data
Memory.
• Literal character strings always reside in Data Memory.
• Although program memory on the ADSP-219x DSPs consists of
24-bit words, only 16 bits of each word are used when C or C++
data is stored in
1-78
keyword extensions to C and C++ that sup-
cc219x
. These keywords can be used to specify the location of
pm
dm
. (This is normally the case for assembly lan-
pm
VisualDSP++ 3.5 C/C++ Compiler and Library Manual
or ) refers to the expression to its
pm
in the declaration.
*
for ADSP-219x DSPs
) or
dm