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54 lines
1013 B
ArmAsm
54 lines
1013 B
ArmAsm
/* https://cirosantilli.com/linux-kernel-module-cheat#x86-loop-instruction */
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#include <lkmc.h>
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LKMC_PROLOGUE
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/* LOOP
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*
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* ....
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* rcx--;
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* if (rcx != 0) goto label
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* ....
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*/
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mov $0, %rax
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mov $3, %rcx
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.Lloop_label:
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inc %rax
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loop .Lloop_label
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LKMC_ASSERT_EQ(%rax, $3)
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/* LOOPE
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*
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* ....
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* rcx--;
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* if (ecx != 0 && ZF == 1) goto label
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* ....
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*
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* Application: search for first non-zero element in a range.
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*
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* If found, rax will contain the element index.
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*
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* Otherwise, rax contains length + 1.
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*/
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.section .rodata
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loope_array: .byte 0, 0, 1, 0
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.text
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/* Array length. */
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mov $4, %rcx
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mov $-1, %rax
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.Lloope_label:
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inc %rax
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cmpb $0, loope_array(%rax)
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loope .Lloope_label
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/* The first non-zero item (1) was at index 2. */
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LKMC_ASSERT_EQ(%rax, $2)
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/* LOOPNE
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*
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* ....
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* ecx--; if (ecx != 0 && ZF == 0) goto lbl
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* ....
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*/
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LKMC_EPILOGUE
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