x86-64

问题 How do I create/handle simple bmp file filling it with one color only using intel 64 bit assembly and nasm assembler? 回答1: The steps that include such operation are: Create bmp file header with fixed values (explanation of specific fields below) Create buffer which contains enough space - three bytes per pixel (one color = red + green + blue) Open/create file Fill the buffer Write header to file Write buffer to file Close file Exit program Ad. 2: This is a bit more tricky - if the number of

问题 I want to build Custom Portable executable using NASM. After getting executable using command nasm -f bin program.asm -o program.exe it crashes and gives error similar to this Below you can see the code. bits 64 %define BASE 400000h ALIGNMENT equ 512 %define SECTALIGN 8192 STD_OUTPUT_HANDLE equ -11 NULL equ 0 %define ROUND(v, a) (((v + a - 1) / a) * a) %define ALIGNED(v) (ROUND(v, ALIGNMENT)) %define RVA(obj) (obj - BASE) section header progbits start=0 vstart=BASE mz_hdr: dw "MZ" ; DOS magic

问题 I want to build Custom Portable executable using NASM. After getting executable using command nasm -f bin program.asm -o program.exe it crashes and gives error similar to this Below you can see the code. bits 64 %define BASE 400000h ALIGNMENT equ 512 %define SECTALIGN 8192 STD_OUTPUT_HANDLE equ -11 NULL equ 0 %define ROUND(v, a) (((v + a - 1) / a) * a) %define ALIGNED(v) (ROUND(v, ALIGNMENT)) %define RVA(obj) (obj - BASE) section header progbits start=0 vstart=BASE mz_hdr: dw "MZ" ; DOS magic

问题 first, if somebody knows a function of the Standard C Library, that prints a string without looking for a binary zero, but requires the number of characters to draw, please tell me! Otherwise, I have this problem: void printStringWithLength(char *str_ptr, int n_chars){ asm("mov 4, %rax");//Function number (write) asm("mov 1, %rbx");//File descriptor (stdout) asm("mov $str_ptr, %rcx"); asm("mov $n_chars, %rdx"); asm("int 0x80"); return; } GCC tells the following error to the "int" instruction:

问题 first, if somebody knows a function of the Standard C Library, that prints a string without looking for a binary zero, but requires the number of characters to draw, please tell me! Otherwise, I have this problem: void printStringWithLength(char *str_ptr, int n_chars){ asm("mov 4, %rax");//Function number (write) asm("mov 1, %rbx");//File descriptor (stdout) asm("mov $str_ptr, %rcx"); asm("mov $n_chars, %rdx"); asm("int 0x80"); return; } GCC tells the following error to the "int" instruction:

问题 I have a problem with my assembly code (64 bit masm in Visual 2013 on win8 64). When I'm calling C function (printf), it throwing exception from ntdll.dll. What I'm doing wrong? How I can read and write data from console in 64 bit masm? Where I can find good tutorial for masm 64 bit? extrn printf : proc .data format byte "Arg1: %d", 10, 0 .code printData proc mov rbx, 100 push rbx lea rax, format; format address push rax call printf; throw unhandled exception ntdll.dll - Access violation

问题 The paper N4455 No Sane Compiler Would Optimize Atomics talks about various optimizations compilers can apply to atomics. Under the section Optimization Around Atomics, for the seqlock example, it mentions a transformation implemented in LLVM, where a fetch_add(0, std::memory_order_release) is turned into a mfence followed by a plain load, rather than the usual lock add or xadd . The idea is that this avoids taking exclusive access of the cacheline, and is relatively cheaper. The mfence is

问题 The paper N4455 No Sane Compiler Would Optimize Atomics talks about various optimizations compilers can apply to atomics. Under the section Optimization Around Atomics, for the seqlock example, it mentions a transformation implemented in LLVM, where a fetch_add(0, std::memory_order_release) is turned into a mfence followed by a plain load, rather than the usual lock add or xadd . The idea is that this avoids taking exclusive access of the cacheline, and is relatively cheaper. The mfence is

问题 I am using the following code to set the cr0 bit to disable cache. When I compile this #include <stdio.h> int main() { __asm__("pushl %eax\n\t" "mov %cr0,%eax;\n\t" "orl $(1 << 30),%eax;\n\t" "mov %eax,%cr0;\n\t" "wbinvd\n\t" "popl %eax" ); return 0; } I am getting error saying that the operands are invalid for mov. Can anyone please point me to a good gcc x86-64 guide for doing these kinds of things? Also what exactly is wrong with the above code? 回答1: Ok, so finally I wrote the following

问题 I am using the following code to set the cr0 bit to disable cache. When I compile this #include <stdio.h> int main() { __asm__("pushl %eax\n\t" "mov %cr0,%eax;\n\t" "orl $(1 << 30),%eax;\n\t" "mov %eax,%cr0;\n\t" "wbinvd\n\t" "popl %eax" ); return 0; } I am getting error saying that the operands are invalid for mov. Can anyone please point me to a good gcc x86-64 guide for doing these kinds of things? Also what exactly is wrong with the above code? 回答1: Ok, so finally I wrote the following