spin.s

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; ***** BEGIN LICENSE BLOCK *****
; Source last modified: $Id: spin.s,v 1.1.32.3 2004/07/09 01:47:21 hubbe Exp $
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;
;
;  spin.s:  Example assembly language routine for spinlock support.
;
;
; XXXDC -- Since the caller has aligned the pointer I simplified this
; routine by eliminating this code.  The pointer must be 16-byte aligned
; for a 32-bit environment.
;
; Also, couldn't we eliminate the nop's?  This is only needed for
; old hardware.
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    .code
;   .level 2.0W                 ; use this option for 64-bit assembly
    .export load_and_clear,entry,priv_lev=3,rtnval=gr
    .proc
load_and_clear
    .callinfo no_calls
    .enter

; create a 16 byte aligned pointer to the load+clear word area
    addi        15,%arg0,%arg2  ; add 15 to pointer provided to round up

; Choose one of these statements and comment out the other:
    depi        0,31,4,%arg2    ; mask off the lower 4 bits (32-bit version)
;;   depdi       0,63,4,%arg2    ; mask off the lower 4 bits (64-bit version)

		
; load and clear the spinlock.  If locked, return 0
    stbys,e     0,(%arg2)       ; scrub cache; important for performance
    ldcws       (%arg2),%ret0   ; load and clear the spinlock word
    nop                         ; 3 No-Op instructions; needed for older
    nop                         ; HP-PA chips
    nop
    bv,n        (%r2)
    .leave
    .procend

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;;OLD OLD OLD 
;;
; create a 16 byte aligned pointer to the load+clear word area
;    addi        15,%arg0,%arg2  ; add 15 to pointer provided to round up
;
; Choose one of these statements and comment out the other:
;    depi        0,31,4,%arg2    ; mask off the lower 4 bits (32-bit version)
;;   depdi       0,63,4,%arg2    ; mask off the lower 4 bits (64-bit version)
;
; load and clear the spinlock.  If locked, return 0
;    stbys,e     0,(%arg2)       ; scrub cache; important for performance
;    ldcws       (%arg2),%ret0   ; load and clear the spinlock word
;    nop                         ; 3 No-Op instructions; needed for older
;    nop                         ; HP-PA chips
;    nop
;    bv,n        (%r2)
;    .leave
;    .procend
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