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Series Article Directory

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foreword

1. Inline Assembly (Inline Assembly)

1.1、asm!

1.2. Parameters of asm macros

Summarize

foreword

Rust introduced inline assembly support in version 1.59, which is very useful for applications that require low-level control, such as controlling low-level execution, accessing specific machine instructions, and so on.

For the main teaching material, please refer to "The Rust Programming Language".
For the main teaching material, please refer to "Rust For Rustaceans". For the main teaching material, please refer to "
The Rustonomicon ".

1. Inline Assembly (Inline Assembly)

1.1、asm!

Using asm!and global_asm!macros , the assembly language and instructions used in inline assembly depend on the corresponding machine platform, so far Rust supports inline assembly for the following platforms

x86 and x86-64
ARM
AArch64
RISC-V
LoongArch

If not supported, the asm! macro will trigger an error.

use std::arch::asm;

// Multiply x by 6 using shifts and adds
let mut x: u64 = 4;
unsafe {
    
    
    asm!(
        "mov {tmp}, {x}",
        "shl {tmp}, 1",
        "shl {x}, 2",
        "add {x}, {tmp}",
        x = inout(reg) x,
        tmp = out(reg) _,
    );
}
assert_eq!(x, 4 * 6);

1.2. Parameters of asm macros

These parameters are for the compiler to help allocate registers

in: Indicates that the variable value is passed to the register
out : Indicates that the value of the register is written to the variable
inout: Instant input is also output, this way can guarantee the same register to complete the task
lateout: any output that is only written after all input has been consumed
inlateout: the output value is not modified until all registers are read;
sym: asm can aggregate symbol relocations to read from thread-local data

For the specific content, we will put it in the part of Rust embedded explanation, which is not the focus of our series at present

Summarize

The above content is to explain Rust's inline assembly

[Learn Rust programming with Xiaojia] 24. Inline assembly (inline assembly)