Using Assembly Language with C - Using the GNU Compiler Collection (GCC)
Description: Using the GNU Compiler Collection (GCC)

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### 6.44 How to Use Inline Assembly Language in C Code

The `asm` keyword allows you to embed assembler instructions within C code. GCC provides two forms of inline `asm` statements. A basic `asm` statement is one with no operands (see Basic Asm), while an extended `asm` statement (see Extended Asm) includes one or more operands. The extended form is preferred for mixing C and assembly language within a function, but to include assembly language at top level you must use basic `asm`.

You can also use the `asm` keyword to override the assembler name for a C symbol, or to place a C variable in a specific register.