asm keyword allows you to embed assembler instructions
within C code. GCC provides two forms of inline
statements. A basic
asm statement is one with no
operands (see Basic Asm), while an extended
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
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.