$ gcc -c sha256_xmm_amd64_atom.asm
gcc: sha256_xmm_amd64_atom.asm: linker input file unused because linking not done

$ yasm !$
yasm sha256_xmm_amd64_atom.asm
sha256_xmm_amd64_atom.asm:26: warning: binary object format does not support extern variables
sha256_xmm_amd64_atom.asm:28: warning: binary object format does not support global variables
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references
sha256_xmm_amd64_atom.asm:216: error: binary object format does not support external references

$ gcc sha256_xmm_amd64_atom.asm 
/usr/bin/ld:sha256_xmm_amd64_atom.asm: file format not recognized; treating as linker script
/usr/bin/ld:sha256_xmm_amd64_atom.asm:1: syntax error
collect2: ld returned 1 exit status

$ mv sha256_xmm_amd64_atom.asm sha256_xmm_amd64_atom.s
$ gcc sha256_xmm_amd64_atom.s
sha256_xmm_amd64_atom.s: Assembler messages:
sha256_xmm_amd64_atom.s:1: Error: no such instruction: `sha-256 for X86-64 for Linux,based off of:'
sha256_xmm_amd64_atom.s:3: Error: junk at end of line, first unrecognized character is `('
sha256_xmm_amd64_atom.s:4: Error: no such instruction: `version 2011'
[... some screenfuls ...]

$ mv sha256_xmm_amd64_atom.s sha256_xmm_amd64_atom.S
$ gcc sha256_xmm_amd64_atom.S 
[identical]
$ as sha256_xmm_amd64_atom.S 
[identical]

$ as --version
GNU assembler (GNU Binutils for Ubuntu) 2.21.0.20110327
Copyright 2011 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or later.
This program has absolutely no warranty.
This assembler was configured for a target of `x86_64-linux-gnu'.

    given ($cmd) {
        when ('buy') {
            if ($args[0] =~ /^([0-9.]+)%$/) {
                my $pct = $1;
                my $b = $m->get_balance;   ## $m is an MtGox object
                $args[0] = sprintf '$%.3f', $b->{'usds'} * $pct / 100;
                ## don't continue, fall to the next if
            }
            if ($args[0] =~ /^\$([0-9.]+)$/ or $args[0] =~ /^([0-9.]+)\$$/) {
                my $usds = $1;
                my $t = $m->get_ticker;
                my $sell = $t->{'ticker'}{'sell'};

                $args[0] = $usds / $sell;
                ## don't continue, now the code proceeds to buy
            }
            $m->buy (amount => $args[0], price => $args[1]);