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#
# Copyright (C) 2001-2004 Jakub Jermar
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.text

.global has_cpuid


## Determine CPUID support
#
# Return 0 in EAX if CPUID is not supported, 1 if supported.
#
has_cpuid:
    pushf           # store flags
    popl %eax       # read flags
    movl %eax,%edx      # copy flags
    btcl $21,%edx       # swap the ID bit
    pushl %edx
    popf            # propagate the change into flags
    pushf
    popl %edx       # read flags    
    andl $(1<<21),%eax  # interested only in ID bit
    andl $(1<<21),%edx
    xorl %edx,%eax      # 0 if not supported, 1 if supported
    ret