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[/] [c0or1k/] [trunk/] [src/] [arch/] [arm/] [v6/] [mutex.S.ARM] - Blame information for rev 6

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1 2 drasko 
/*
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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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