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How to write to flash memory using inline assembly?


How to write to flash memory using inline assembly?

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How to write to flash memory using inline assembly?
Tag : c , By : Suresh S
Date : November 25 2020, 07:06 PM


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C inline assembly memory copy


Tag : c , By : DotNetWise
Date : March 29 2020, 07:55 AM
wish helps you Your inline assembler code is broken. You can't directly use EAX and EBX without adding them to the clobber list. Otherwise the compiler does not now which registers have been modified.
It is very likely that one of the registers that you've modified contained something damn important that later caused the segmentation fault.
asm (
 "movl (%0), %%eax \n\t" /* read first dword from array1 into eax */
 "movl %%eax, (%1) \n\t" /* write dword into array2
 : /* outputs */
 : /* inputs */ "r"(array1),"r"(array2)
 : /* clobber */ "eax", "memory"
);
int dummy;
asm (
 "movl (%1), %0 \n\t"
 "movl %0, (%2) \n\t"
 : /* outputs, temps.. */ "=r" (dummy) 
 : /* inputs */           "r"(array1),"r"(array2)
 : /* clobber */          "memory"
);

Why are there two ways to write inline assembly with gcc?


Tag : gcc , By : Joshua Johnson
Date : March 29 2020, 07:55 AM
wish of those help The C standard reserves 'asm' for use by users for any purpose. Therefore, GCC provides the __asm__ notation to avoid running into the user's name space (because identifiers starting with double underscore are reserved for the implementation).
The notation with the double underscore is ungainly, so GCC provides the pleasanter interface without the double underscores. But if you turn on a standard-compliant compilation mode (such as -std=c99), the asm option is turned off. By writing with the double underscore notation, it is always available.

How to write inline assembly in FreeDOS


Tag : c , By : Kocur
Date : March 29 2020, 07:55 AM
wish help you to fix your issue Things like for, address and printf are not part of assembly. You will have to rewrite that to actual assembly code or copy the macros and assembler you want to use to your freedos environment.
If you want to use debug as included in freedos you can use the a command to start writing assembly instructions, the n command to give a name and w to write the code to the file.
C:\debug
-a
06BC:0100 int 20
06BC:0102
-n ivtdump.com
-rcx 2
-w
Writing 0002 bytes.
-q

C:\

Clobbered memory in two inline assembly calls vs in one inline assembly call?


Tag : cpp , By : kdietz
Date : March 29 2020, 07:55 AM
I wish this helpful for you Options 1 & 2 would let the CPUID itself reorder with unrelated non-volatile loads/stores (in one direction or the other). This is very likely not what you want.
You could put a memory barrier on both sides of CPUID, but it's certainly better to just make CPUID a memory barrier itself.
void foo(int level){
    int eax, ebx, ecx, edx;
    asm volatile("":::"memory");
    asm volatile("CPUID"
        :  "=a"(eax),"=b"(ebx),"=c"(ecx),"=d"(edx)
        :  "0"(level)
        :
    );
}

# x86-64 gcc7.3  -O3 -fverbose-asm

    pushq   %rbx  #           # rbx is call-preserved, but we clobber it.
    movl    %edi, %eax      # level, eax
    CPUID
    popq    %rbx    #
    ret
void modify_level(int level){
    level += 1;                  // modify level before the barrier
    int eax, ebx, ecx, edx;
    asm volatile("#mem barrier here":::"memory");
    asm volatile("CPUID"         // then read it after
    :  "=a"(eax),"=b"(ebx),"=c"(ecx),"=d"(edx)
    :  "0"(level):);
}
modify_level(int):
    pushl   %ebx  #
    #mem barrier here
    movl    8(%esp), %eax   # level, tmp97
    addl    $1, %eax        #, level
    CPUID
    popl    %ebx    #
    ret
asm volatile("# memory barrier here":::"memory");

How to write inline Assembly with Turbo C 2.01?


Tag : c , By : Naveen
Date : March 29 2020, 07:55 AM
around this issue See the Turbo C user manual page 430:
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