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44 lines
860 B
ArmAsm
44 lines
860 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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mov $0x81, %r12
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/* Shift left by one. */
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shl %r12b
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LKMC_ASSERT(jc)
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LKMC_ASSERT_EQ(%r12, $2)
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/* Shift left by one. */
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shl %r12b
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LKMC_ASSERT(jnc)
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LKMC_ASSERT_EQ(%r12, $4)
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/* Shift right by one. */
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shr %r12b
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LKMC_ASSERT(jnc)
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LKMC_ASSERT_EQ(%r12, $2)
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/* Shift left by 2 immediate.
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* Differentent coding than shift by 1.
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*/
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shl $2, %r12b
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LKMC_ASSERT(jnc)
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LKMC_ASSERT_EQ(%r12, $8)
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/* Shift left by 2 in cl register. */
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mov $2, %cl
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shl %cl, %r12b
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LKMC_ASSERT(jnc)
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LKMC_ASSERT_EQ(%r12, $0x20)
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#if 0
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/* cl is the only possible register choice
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* Error: operand type mismatch for `shr'
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*/
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shr %bl, %ax
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#endif
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LKMC_EPILOGUE
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