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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 1 | jermar | 1 | # |
| 2 | # Copyright (C) 2001-2004 Jakub Jermar |
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| 3 | # All rights reserved. |
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| 4 | # |
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| 5 | # Redistribution and use in source and binary forms, with or without |
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| 6 | # modification, are permitted provided that the following conditions |
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| 7 | # are met: |
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| 8 | # |
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| 9 | # - Redistributions of source code must retain the above copyright |
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| 10 | # notice, this list of conditions and the following disclaimer. |
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| 11 | # - Redistributions in binary form must reproduce the above copyright |
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| 12 | # notice, this list of conditions and the following disclaimer in the |
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| 13 | # documentation and/or other materials provided with the distribution. |
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| 14 | # - The name of the author may not be used to endorse or promote products |
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| 15 | # derived from this software without specific prior written permission. |
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| 16 | # |
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| 17 | # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | # |
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| 28 | |||
| 29 | .text |
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| 30 | |||
| 31 | .global has_cpuid |
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| 32 | |||
| 65 | decky | 33 | |
| 34 | ## Determine CPUID support |
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| 35 | # |
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| 348 | jermar | 36 | # Return 0 in EAX if CPUID is not supported, 1 if supported. |
| 65 | decky | 37 | # |
| 1 | jermar | 38 | has_cpuid: |
| 39 | pushf # store flags |
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| 40 | popl %eax # read flags |
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| 348 | jermar | 41 | movl %eax,%edx # copy flags |
| 42 | btcl $21,%edx # swap the ID bit |
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| 43 | pushl %edx |
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| 1 | jermar | 44 | popf # propagate the change into flags |
| 45 | pushf |
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| 348 | jermar | 46 | popl %edx # read flags |
| 1 | jermar | 47 | andl $(1<<21),%eax # interested only in ID bit |
| 348 | jermar | 48 | andl $(1<<21),%edx |
| 49 | xorl %edx,%eax # 0 if not supported, 1 if supported |
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| 1 | jermar | 50 | ret |