as: GNU Assembler

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1 1.2 The GNU Assembler
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1 GNU 'as' is really a family of assemblers.  If you use (or have used)
1 the GNU assembler on one architecture, you should find a fairly similar
1 environment when you use it on another architecture.  Each version has
1 much in common with the others, including object file formats, most
1 assembler directives (often called "pseudo-ops") and assembler syntax.
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1    'as' is primarily intended to assemble the output of the GNU C
1 compiler 'gcc' for use by the linker 'ld'.  Nevertheless, we've tried to
1 make 'as' assemble correctly everything that other assemblers for the
1 same machine would assemble.  Any exceptions are documented explicitly
1 (⇒Machine Dependencies).  This doesn't mean 'as' always uses the
1 same syntax as another assembler for the same architecture; for example,
1 we know of several incompatible versions of 680x0 assembly language
1 syntax.
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1    Unlike older assemblers, 'as' is designed to assemble a source
1 program in one pass of the source file.  This has a subtle impact on the
1 '.org' directive (⇒'.org' Org.).
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