math64.s

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

;/* ***** BEGIN LICENSE BLOCK ***** 
; * Version: RCSL 1.0/RPSL 1.0 
; *  
; * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
; *      
; * The contents of this file, and the files included with this file, are 
; * subject to the current version of the RealNetworks Public Source License 
; * Version 1.0 (the "RPSL") available at 
; * http://www.helixcommunity.org/content/rpsl unless you have licensed 
; * the file under the RealNetworks Community Source License Version 1.0 
; * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, 
; * in which case the RCSL will apply. You may also obtain the license terms 
; * directly from RealNetworks.  You may not use this file except in 
; * compliance with the RPSL or, if you have a valid RCSL with RealNetworks 
; * applicable to this file, the RCSL.  Please see the applicable RPSL or 
; * RCSL for the rights, obligations and limitations governing use of the 
; * contents of the file.  
; *  
; * This file is part of the Helix DNA Technology. RealNetworks is the 
; * developer of the Original Code and owns the copyrights in the portions 
; * it created. 
; *  
; * This file, and the files included with this file, is distributed and made 
; * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
; * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
; * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS 
; * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 
; * 
; * Technology Compatibility Kit Test Suite(s) Location: 
; *    http://www.helixcommunity.org/content/tck 
; * 
; * Contributor(s): 
; *  
; * ***** END LICENSE BLOCK ***** */ 

;/* assembly.s
; * 
; * the assembly routines are written in this separate .s file because EVC++ won't inline...
; *
; * Notes on APCS (ARM procedure call standard):
; *  - first four arguments are in r0-r3
; *  - additional argumets are pushed onto stack in reverse order
; *  - return value goes in r0
; *  - routines can overwrite r0-r3, r12 without saving
; *  - other registers must be preserved with stm/ldm commands
; * 
; * Equivalent register names:
; *
; * r0  r1  r2  r3  r4  r5  r6  r7  r8  r9  r10 r11 r12 r13 r14 r15
; * ---------------------------------------------------------------
; * a1  a2  a3  a4  v1  v2  v3  v4  v5  v6  sl  fp  ip  sp  lr  pc
; */

	INCLUDE kxarm.h
	TEXTAREA

; int MULSHIFT32(int x, int y)
	LEAF_ENTRY MulShift32

	smull r2,r0,r1,r0
	mov   pc, lr			

	ENTRY_END MulShift32

; int MulShift31(int x, int y)
	LEAF_ENTRY MulShift31

	smull r2,r0,r1,r0
	mov   r2,r2,lsr #31
	orr   r0,r2,r0,lsl #1

	mov   pc, lr			

	ENTRY_END MulShift31

; int MULSHIFT30(int x, int y)
	LEAF_ENTRY MulShift30

	smull r2,r0,r1,r0
	mov   r2,r2,lsr #30
	orr   r0,r2,r0,lsl #2

	mov   pc, lr			

	ENTRY_END MulShift30

; int MulShiftN(int x, int y, int n)
	LEAF_ENTRY MulShiftN

	smull r3,r0,r1,r0  ; r0 hi, h3 lo
	mov   r3,r3,lsr r2 ; shift lo right by r2 
	rsb   r2,r2,#32
	orr   r0,r3,r0,lsl r2 ; shift hi left by 32-r2, and or in

	mov   pc, lr			

	ENTRY_END MulShiftN

	END