abs_s.asm

来自「It is source code for Melp2.4kps vocoder」· 汇编 代码 · 共 92 行

* 
* 
*2.4 kbps MELP Proposed Federal Standard speech coder
*
*TMS320C5x assembly code
*
*version 1.0
*
*Copyright (c) 1998, Texas Instruments, Inc.  
*
*Texas Instruments has intellectual property rights on the MELP
*algorithm.  The Texas Instruments contact for licensing issues for
*commercial and non-government use is William Gordon, Director,
*Government Contracts, Texas Instruments Incorporated, Semiconductor
*Group (phone [phone]).
*
*
*************************************************************************
*
* The following code was hand optimized for the Texas Instuments
* TMS320C5x DSP by DSPCon, Inc.  For information, please contact DSPCon
* at:
* 
*                       DSPCon, Inc.
*                       380 Foothill Road
*                       Bridgewater, New Jersey 08807
*                       [phone]
*                       [e-mail]
*                       www.dspcon.com
*
*************************************************************************
	.if 0
/***************************************************************************
 *
 *   FUNCTION NAME: abs_s
 *
 *   PURPOSE:
 *
 *     Take the absolute value of the 16 bit input.  An input of
 *     -0x8000 results in a return value of 0x7fff.
 *
 *   INPUTS:
 *
 *     var1
 *		       16 bit short signed integer (Shortword) whose value
 *		       falls in the range 0xffff 8000 <= var1 <= 0x0000 7fff.
 *
 *   OUTPUTS:
 *
 *     none
 *
 *   RETURN VALUE:
 *
 *     swOut
 *		       16 bit short signed integer (Shortword) whose value
 *		       falls in the range
 *		       0x0000 0000 <= swOut <= 0x0000 7fff.
 *
 *   IMPLEMENTATION:
 *
 *     Take the absolute value of the 16 bit input.  An input of
 *     -0x8000 results in a return value of 0x7fff.
 *
 *   KEYWORDS: absolute value, abs
 *
 *************************************************************************/
	.endif
;  Code to perform the Absolute value of a 16 signed values

    .mmregs

    .def    _abs_s

FP	.set	AR0
SP	.set	AR1

    .text

; Save C context so that we may restore it upon exit
_abs_s	.equ	$

; Take stack passed arguments
    MAR     *-		; Point SP to first argument
    SSXM

; Prepare to return to caller
exit:
    RETD		; return to caller with delay
	LAC *+		; Load input argument
	ABS		; Take absulute value of input
    .end