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43 lines
1008 B
ArmAsm
43 lines
1008 B
ArmAsm
/* https://github.com/cirosantilli/linux-kernel-module-cheat#x86-binary-arithmetic-instructions
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*
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* Signed multiply.
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*
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* Has many more forms than MUL including immediate and up to three arguments.
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*/
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#include <lkmc.h>
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LKMC_PROLOGUE
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/* The single register forms are just like MUL, and
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* extend over rdx:rax.
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*
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* rdx : rax = rax * rbx
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* = -1 * 2
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* = -2
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* = 0xFFFFFFFFFFFFFFFF : 0xFFFFFFFFFFFFFFFE
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*/
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mov $-1, %rax
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mov $2, %rbx
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mov $42, %rdx
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imul %rbx
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mov %rax, %r12
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mov %rdx, %r13
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LKMC_ASSERT_EQ(%r12, $0xFFFFFFFFFFFFFFFE)
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LKMC_ASSERT_EQ(%r13, $0xFFFFFFFFFFFFFFFF)
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/* The multi-argument formas don't extend over rdx, but
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* are more convenient in many cases.
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*
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* rax = rbx * 3
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*/
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mov $42, %rax
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mov $-2, %rbx
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mov $42, %rdx
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imul $3, %rbx, %rax
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mov %rax, %r12
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mov %rdx, %r13
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LKMC_ASSERT_EQ(%r12, $-6)
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LKMC_ASSERT_EQ(%r13, $42)
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LKMC_EPILOGUE
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