ARM Technical Support Knowledge Articles

USERSTACKDPP3 DIRECTIVE

Applies to: C166 C Compiler

Answer


Information in this article applies to:


QUESTION

What does the USERSTACKDPP3 directive do?

ANSWER

The USERSTACKDPP3 directive, abbreviated U3, changes the assumptions made by the C166 Compiler regarding accesses to the user stack area.

By default, the user stack is located in the NDATA memory area and is accessed with DPP2. To locate the user stack in the IDATA or SDATA memory classes (which is accessed using DPP3), you must use the USERSTACKDPP3 directive and you must make the following changes to the definition of the user stack and the initialization of the user stack pointer (R0) in the startup code:

The changes are highlighted and shown with 'SDATA'. 'IDATA' works the same way.

STARTUP.A66 or START167.A66

    ?C_USERSTACK   SECTION   DATA PUBLIC 'NDATA'
to:
    ?C_USERSTACK   SECTION   DATA PUBLIC 'SDATA'
    NDATA  DGROUP  ?C_USERSTACK
to:
    SDATA  DGROUP  ?C_USERSTACK

In addition, you must change the following line:

    MOV    R0,#DPP2:?C_USERSTKTOP
to:
    MOV    R0,#DPP3:?C_USERSTKTOP

 

START_V2.A66

    ?C_USERSTACK   SECTION DATA PUBLIC 'NDATA'
    :
    ?C_USERSTACK1  SECTION DATA PUBLIC 'NDATA'
    :
    ?C_USERSTACK2  SECTION DATA PUBLIC 'NDATA'
to:
    ?C_USERSTACK   SECTION DATA PUBLIC 'SDATA'
    :
    ?C_USERSTACK1  SECTION DATA PUBLIC 'SDATA'
    :
    ?C_USERSTACK2  SECTION DATA PUBLIC 'SDATA'
    NDATA  DGROUP  ?C_USERSTACK, ?C_USERSTACK1, ?C_USERSTACK2
    :
    NDATA  DGROUP  ?C_USERSTACK, ?C_USERSTACK1
    :
    NDATA  DGROUP  ?C_USERSTACK, ?C_USERSTACK2
    :
    NDATA  DGROUP  ?C_USERSTACK
to:
    SDATA  DGROUP  ?C_USERSTACK, ?C_USERSTACK1, ?C_USERSTACK2
    :
    SDATA  DGROUP  ?C_USERSTACK, ?C_USERSTACK1
    :
    SDATA  DGROUP  ?C_USERSTACK, ?C_USERSTACK2
    :
    SDATA  DGROUP  ?C_USERSTACK

In addition, you must change the following line:

    MOV    R0,#?C_USERSTKTOP1
    :
    MOV    R0,#?C_USERSTKTOP2
    :
    MOV    R0,#?C_USERSTKTOP
to:
    MOV    R0,#DPP3:?C_USERSTKTOP1
    :
    MOV    R0,#DPP3:?C_USERSTKTOP2
    :
    MOV    R0,#DPP3:?C_USERSTKTOP

SEE ALSO

Article last edited on: 2006-03-13 10:49:13

Rate this article

[Bad]
|
|
[Good]
Disagree? Move your mouse over the bar and click

Did you find this article helpful? Yes No

How can we improve this article?

Link to this article
Copyright © 2011 ARM Limited. All rights reserved. External (Open), Non-Confidential