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.