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Altera_Forum
Honored Contributor I
1,196 Views

Manually Assigning C Code to a Specific Memory Section

Hi, everybody. 

I want to place some code, that is critical in fast onchip memory. I've read in "Nios II Software Developer's Book" from Altera's site this:  

 

"Within your program source code, you can specify a target memory 

section for a specific piece of code. To do this action in C or C++, you can 

use the section attribute. The following code shows placing a variable 

foo within the memory named on_chip_memory, and the function 

bar()in the memory named sdram. 

 

Use the extension .txt for code, and the extension .rodata for 

read-only data or .rwdata for read-write data. 

 

Example: Manually Assigning C Code to a Specific Memory Section 

 

/* data should be initialized when using the section attribute */ 

int foo __attribute__ ((section (".on_chip_memory.rwdata"))) = 0; 

void bar __attribute__ ((section (".sdram.txt"))) (void) 

foo++; 

}" 

 

I'm using Nios II IDE, have onchip memory generated in SOPC Builder named onchip_memory_0, and I want to place my interrupt service routine in this memory. For program, read only, heap, stack, and read/write memory in system description in Nios II IDE I choose sram. I can define variable in this memory like this: 

 

int foo __attribute__ ((section (".onchip_memory_0.rwdata"))) = 0; 

 

,but if I try to place there function like this: 

 

void function __attribute__ ((section (".onchip_memory_0.text"))) (void) 

foo++; 

 

compiler returns errors: 

1) parse error before "(" ,and 

2) size of function isn't known 

 

What's happening? What must I do? Have I write my own linker script instead of automatically written by Nios II IDE, or something?
0 Kudos
3 Replies
Altera_Forum
Honored Contributor I
92 Views

Shouldn't you be using ".txt" instead of ".text"?

Altera_Forum
Honored Contributor I
92 Views

No, I've tried both. I think that in pdf it is a bug, and it should be text. I've tried .txt, .text, without .something, and have same errors.

Altera_Forum
Honored Contributor I
92 Views

I haven't looked at this, but I think that "Nios2 Forum" should have something more suitable to address your issue.

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