Re: [Mspgcc-users] asm("address") and -fdata-sections

[Mathias K. <ke...@fr...>]

Hello,

the RAM starts at 2400 and your variable is placed before this address. You can simple use a pointer
or define to access this buffer. Anyway the Pointer for the EP0 buffer is defined in the msp430
header files.

#include <msp430.h>
#include <stdint.h>
#include <string.h>

#define EP0_MAX_PACKET_SIZE 0x08

#define iep0_buf (((uint8_t*)(int)USBIEP0BUF_))

int main()
{
 memset(iep0_buf, 0, EP0_MAX_PACKET_SIZE);
 return 0;
}

Assembly looks like this:

    4404:       3d 42           mov     #8,     r13     ;r2 As==11
    4406:       0e 43           clr     r14
    4408:       3f 40 78 23     mov     #9080,  r15     ;#0x2378
    440c:       b0 12 12 44     call    #0x4412


Regards,

Mathias


On 16.02.2013 09:34, Ionut Nicu wrote:
> Hi,
> 
> I have a USB driver for the msp430 5xx series which allocates the USB
> buffers at the proper addresses in the USB RAM using asm("0xaddr")
> statements.
> 
> With the 20120911 compiler, when using "-fdata-sections" the code no
> longer compiles. For example, with the following code:
> 
> #include <msp430.h>
> #include <stdint.h>
> #include <string.h>
> 
> #define EP0_MAX_PACKET_SIZE 0x08
> 
> static uint8_t iep0_buf[EP0_MAX_PACKET_SIZE] asm("0x2378");
> 
> int main()
> {
>         memset(&iep0_buf[0], 0, sizeof(iep0_buf));
>         return 0;
> }
> 
> 
> ionut@heimdall:~$ msp430-gcc -mmcu=msp430f5528 -fdata-sections -c main.c
> -o main.o
> /tmp/ccaEQtpB.s: Assembler messages:
> /tmp/ccaEQtpB.s:8: Error: Missing symbol name in directive
> /tmp/ccaEQtpB.s:8: Error: junk at end of line, first unrecognized
> character is `x'
> /tmp/ccaEQtpB.s:9: Error: expected comma after name `' in .size
> directive
> /tmp/ccaEQtpB.s:10: Error: junk at end of line, first unrecognized
> character is `0'
> 
> 
> If I remove the "-fdata-sections" option, the code compiles just fine.
> 
> In my project, since it's being used for multiple devices, there are a
> lot of things (code and data) that need to be stripped if they're not
> used. That's why I need to use "-fdata-sections -ffunction-sections
> -Wl,--gc-sections" to eliminate data and code that isn't used.
> 
> Trying the same code with the x86 gcc shows the same problem, so I guess
> this is not mspgcc specific, but rather something that changed in newer
> versions of gcc.
> 
> Does anyone have a suggestion on how to solve this? I thought about
> declaring sections for each variable in a custom linker file and then
> using __attribute__((section(".section_name"))) when declaring the
> variables, but I think it's an ugly solution.
> 
> Thanks,
> Ionut.
> 
> 
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