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25 lines
559 B
ArmAsm
25 lines
559 B
ArmAsm
/* https://cirosantilli.com/linux-kernel-module-cheat#x86-shift-and-rotate-instructions */
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#include <lkmc.h>
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LKMC_PROLOGUE
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/* 0xFF == -1 in 2's complement with 8-bits. */
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mov $0xFF, %r12
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sal %r12b
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LKMC_ASSERT(jc)
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/* 0xFE == -2 in 2's complement with 8-bits. */
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LKMC_ASSERT_EQ(%r12, $0xFE)
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/* SAR*/
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sar %r12b
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LKMC_ASSERT(jnc)
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/* -1 */
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LKMC_ASSERT_EQ(%r12, $0xFF)
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/* SAR rounds to -infinity: -1 goes to -1 again. */
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sar %r12b
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LKMC_ASSERT(jc)
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/* -1 */
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LKMC_ASSERT_EQ(%r12, $0xFF)
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LKMC_EPILOGUE
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