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28 lines
701 B
ArmAsm
28 lines
701 B
ArmAsm
/* https://github.com/cirosantilli/linux-kernel-module-cheat#arm-movw-and-movt-instructions */
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#include "common.h"
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ENTRY
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/* movt (top) and movw (TODO what is w) set the higher
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* and lower 16 bits of the register.
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*/
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movw r0, 0xFFFF
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movt r0, 0x1234
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add r0, 1
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ASSERT_EQ(r0, 0x12350000)
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/* movw also zeroes out the top bits, allowing small 16-bit
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* C constants to be assigned in a single instruction.
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*
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* It differs from mov because mov can only encode 8 bits
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* at a time, while movw can encode 16.
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*
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* movt does not modify the lower bits however.
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*/
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ldr r0, =0x12345678
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movw r0, 0x1111
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ASSERT_EQ(r0, 0x00001111)
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EXIT
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