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[/] [c0or1k/] [trunk/] [src/] [arch/] [arm/] [v6/] [mutex.S.ARM] - Diff between revs 2 and 6
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Rev 6 |
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/*
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* ARM v5 Binary semaphore (mutex) implementation.
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*
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* Copyright (C) 2007 Bahadir Balban
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*
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*/
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#include INC_ARCH(asm.h)
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/* Recap on swp:
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* swp rx, ry, [rz]
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* In one instruction:
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* 1) Stores the value in ry into location pointed by rz.
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* 2) Loads the value in the location of rz into rx.
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* By doing so, in one instruction one can attempt to lock
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* a word, and discover whether it was already locked.
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*/
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#define MUTEX_UNLOCKED 0
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#define MUTEX_LOCKED 1
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BEGIN_PROC(__spin_lock)
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mov r1, #1
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__spin:
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swp r2, r1, [r0]
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cmp r2, #0
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bne __spin
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mov pc, lr
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END_PROC(__spin_lock)
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BEGIN_PROC(__spin_unlock)
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mov r1, #0
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swp r2, r1, [r0]
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cmp r2, #1 @ Debug check.
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1:
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bne 1b
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mov pc, lr
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END_PROC(__spin_unlock)
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/*
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* @r0: Address of mutex location.
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*/
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BEGIN_PROC(__mutex_lock)
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mov r1, #1
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swp r2, r1, [r0]
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cmp r2, #0
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movne r0, #0
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moveq r0, #1
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mov pc, lr
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END_PROC(__mutex_lock)
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/*
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* @r0: Address of mutex location.
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*/
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BEGIN_PROC(__mutex_unlock)
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mov r1, #0
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swp r2, r1, [r0]
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cmp r2, #1
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1: @ Debug check.
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bne 1b
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mov pc, lr
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END_PROC(__mutex_unlock)
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/*
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* @r0: Address of mutex location.
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*/
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BEGIN_PROC(__mutex_inc)
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swp r2, r1, [r0]
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mov r1, #1
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swp r2, r1, [r0]
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cmp r2, #0
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movne r0, #0
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moveq r0, #1
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mov pc, lr
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END_PROC(__mutex_inc)
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/*
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* @r0: Address of mutex location.
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*/
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BEGIN_PROC(__mutex_dec)
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mov r1, #0
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swp r2, r1, [r0]
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cmp r2, #1
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1: @ Debug check.
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bne 1b
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mov pc, lr
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END_PROC(__mutex_dec)
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