C++ keyword: asm
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(C++11)
(C++11)
asm
(*)
(C++20)
(C++11)
(C++11)
(C++20)
(C++20)
(C++11)
(C++20)
(C++26)
(C++20)
(C++20)
(C++20)
(C++11)
(C++11)
(C++11)
Identifiers with special meaning
[edit] Usage
[edit] Example
Note that while this example works well with GCC/Clang on x86_64 platform under Linux, it's not guaranteed elsewhere as asm declaration is conditionally-supported and(since C++11) implementation defined.
Run this code
#include <cstring> int main() noexcept { const char* const c_string = "Hello, world!\n"; asm (R"( movq 1,ドル %%rax # syscall number for sys_write movq 1,ドル %%rdi # file descriptor 1 (stdout) movq %0, %%rsi # pointer to the c‐string movq %1, %%rdx # length of the c‐string syscall # invokes an OS system-call handler )" : // no output operands : "r"(c_string), // input: pointer to the c‐string "r"(std::strlen (c_string)) // input: size of the c‐string : "%rax", "%rdi", "%rsi", "%rdx" // clobbered registers ); }
Output:
Hello, world!