p_parity.asm

TI C54写的G729代码,视线8kbps高质量语音编码,汇编优化

;==========================================================================
;  File Name
;  ----------
;  P_PARITY.ASM
;
;  Brief Description of the Code:
;  ------------------------------
;  Parity_pitch - compute parity bit for first 6 MSBs
;
;  Ref
;  ------
;  P_PARITY.C
;==========================================================================

        .mmregs

        .include  ..\include\const.h
        .include  ..\include\tab_ld8a.h
        .include  ..\include\ld8amem.h


;---------------------------------------------------------------------------
;   Parity_Pitch
;---------------------------------------------------------------------------
;   Word16 Parity_Pitch(    /* output: parity bit (XOR of 6 MSB bits)    */
;     Word16 pitch_index   /* input : index for which parity to compute */
;   )
;-----------------------------------------------------------------------
;
;  Input Registers :    B =  pitch_index
;
;  Output Registers :   A =  Word16 Parity_Pitch(Word16 pitch_index)
;
;  Modified Registers : DP, A, B, AR2
;
;---------------------------------------------------------------------------

        .text
        .def    Parity_Pitch

        .asg    "AR2", pZero
	.asg	 "Addr_local_buf2",zero
Parity_Pitch:

        STM     #6 - 1, BRC
		SFTL    B,-2
        ST     #0,*(zero)
        LD      #1, A
        RPTBD   EndParity_Pitch - 1
        STM     #zero, pZero

                SFTL    B, -1		;C(Carry bit)=temp&(Word16)1;
                ADDC    *pZero, A
EndParity_Pitch:

        RETD
        AND     #1, A