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Hi,
I am trying to migrate my project to ARM compiler 6.19 from an older version (5.xx).
In Compiler 5.xx, I know that the asm instruction "PRESERVE8" is used to specify that the current file preserves the eight-byte alignment of the stack.
This instruction is causing a linker error and I couldn't find any translation in the document "Migrate ARM Compiler 5 to ARM Compiler 6" or any other online forum.
How do I rewrite this instruction compatible with ARM Compiler 6? Is there any documentation available that describes how to resolve this issue?
Any help is much appreciated. Thank you
Well I did, but I get error as I already mention before:: error: use of undeclared identifier 'PRESERVE8'
: error: use of undeclared identifier 'PRESERVE8'
The code is like that:
void test(void)
{
PRESERVE8;
__asm(
"THUMB"
"PUSH {r0-r3,lr}"
...
It would be something like:
void test(void) { __asm{ "PUSH {r0-r3,lr}" } ...
See developer.arm.com/.../Inline-assembly-with-Arm-Compiler-for-Embedded-6
Are you sure I need to use curly brackets?
From the compiler user manual and reference manual. I also checked the link you provided and after the __asm I need to use normal brackets ().
And I dont see where you put the PRESERVE8 ? Also THUMB is not recognized.
Best regards, Frenk
Apologies for the bracketing typo.
You would not specify PRESERVE8 (or THUMB). Again, the inline/embedded assembler is not the same as the 'full' assembler.
Ok, I understand.
So for inline assembly I dont need to specify this 2 statements as armclang will use them automatically OR do I need to specify any specific flag for this? I know armclang has -mthumb (which is set but also set by default) and in the armlink I can specify 8 byte alignment. But do I need to specify anything else?
I am porting from the very old code and there is everything written :-), so now I have to figure out how to port it to new armclang and this is a working example (check how to call C function and that at end of each line you need \n\t otherwise build fails):
void test(void){ __asm{ "PUSH {r0-r3,lr}\n\t"
__asm{
"PUSH {r0-r3,lr}\n\t"
"BL testC\n\t"
Best regards, Iknerf
I don't think there is any special flag needed.
Compiling for Cortex-M implies Thumb code (they do not have the concept of Arm and Thumb state).
I appreciate that porting such code can be a non-trivial task.