Mixing c & assembly in Keil IDE

[lakshman]

Dear Nordic, Whats wrong with the below code. It works well in RFduino but when I try to port the same code in Keil environment.Its not working throwing error as 1.identifier "asm is undefined 2. expected a ";" code below

void mixC_and_Assembly()
{
 volatile uint32_t  *out = &NRF_GPIO->OUT;
 byte *_ptbytes = txBuf;
 byte *_ptbytes1 = &txBuf[32];
 uint32_t  rbyte;

   // out =%0
   //_ptbytes = %1
   //rbyte = %2
  asm  volatile
  ( 
       //"headSP:\n\t"
       "push {r0,r1,r2,r3}\n\t"
       
        "ldrb %2, [%1,#0]\n\t"    //    rbyte = *_ptbytes
        "str %2,[%0,#0] \n\t"    //  *out = _ptbytes[0]

        "ldrb %2,[%1,#1] \n\t"    //  rbyte = *_ptbytes
        "str %2,[%0,#0] \n\t"    //  *out = _ptbytes[1]
       
        "ldrb %2,[%1,#2] \n\t"    //  rbyte = *_ptbytes
        "str %2,[%0,#0] \n\t"    //  *out = _ptbytes[2]

        ......
        .....
        .....
        ......
        
        
        "pop {r0,r1,r2,r3} \n\t" 
    ::
    "r" (out),   // %0
    "r" (_ptbytes),   // %1
    "r" (rbyte), //%2
    "r" (_ptbytes1)   // %3
    :"memory"
  );
}

after going through core_cmo.h file I have changed asm into __asm

void mixC_and_Assembly()
{
 volatile uint32_t  *out = &NRF_GPIO->OUT;
 byte *_ptbytes = txBuf;
 byte *_ptbytes1 = &txBuf[32];
 uint32_t  rbyte;

   // out =%0
   //_ptbytes = %1
   //rbyte = %2

  __asm  volatile
  ( 
       //"headSP:\n\t"
       "push {r0,r1,r2,r3}\n\t"
       
        "ldrb %2, [%1,#0]\n\t"    //    rbyte = *_ptbytes
        "str %2,[%0,#0] \n\t"    //  *out = _ptbytes[0]

        "ldrb %2,[%1,#1] \n\t"    //  rbyte = *_ptbytes
        "str %2,[%0,#0] \n\t"    //  *out = _ptbytes[1]
       
        "ldrb %2,[%1,#2] \n\t"    //  rbyte = *_ptbytes
        "str %2,[%0,#0] \n\t"    //  *out = _ptbytes[2]

        ......
        .....
        .....
        ......
        
        
        "pop {r0,r1,r2,r3} \n\t" 
    ::
    "r" (out),   // %0
    "r" (_ptbytes),   // %1
    "r" (rbyte), //%2
    "r" (_ptbytes1)   // %3
    :"memory"
  );
}

still I am getting error as "expected ")" ". is there anything I need to add in compiler option in keil ? kindly advise Thanks and Regards Lakshman,PMP,PMI-RMP

[Hung Bui]

Hi Lakshman,

You can find an example of using ASM with C in KEIL in the bootloader_util.c for the bootloader project in our SDK. You can find the file in \components\libraries\bootloader_dfu

[Vidar Berg]

Just like to add that the asm syntax is not the same for Keil and the GNU arm toolchain. bootloader_util.c shows the difference as Hung pointed out (SDK v8.1.0+).