as now supports assembly using Intel assembler syntax.
.intel_syntax selects Intel mode, and
.att_syntax switches back to the usual AT&T mode for compatibility with the output of
gcc. Either of these directives may have an optional argument,
noprefix specifying whether registers require a ‘%’ prefix. AT&T System V/386 assembler syntax is quite different from Intel syntax. We mention these differences because almost all 80386 documents use Intel syntax. Notable differences between the two syntaxes are:
In 64-bit code, ‘movabs’ can be used to encode the ‘mov’ instruction with the 64-bit displacement or immediate operand.