basic_op.h

音频编解码库的具体实现,分析流程清晰,编译测试通过

#ifndef _BASIC_OP_H
#define _BASIC_OP_H

/*___________________________________________________________________________
 |                                                                           |
 |   Constants and Globals                                                   |
 |                                                                           |
 | $Id $
 |___________________________________________________________________________|
*/
//extern Flag Overflow;
//extern Flag Carry;
Flag Overflow;
Flag Carry;


#define MAX_32 (Word32)0x7fffffffL
#define MIN_32 (Word32)0x80000000L

#define MAX_16 (Word16)0x7fff
#define MIN_16 (Word16)0x8000

#define UMAX_32 (Word32)0xffffffffL
#define UMIN_32 (Word32)0x00000000L

#define UMAX_16 (Word16)0xffff
#define UMIN_16 (Word16)0x0000

#define ALIGN_8  __declspec(align(8)) 
#define ALIGN_16  __declspec(align(16)) 

/*___________________________________________________________________________
 |                                                                           |
 |   Prototypes for basic arithmetic operators                               |
 |___________________________________________________________________________|
*/

Word16 add (Word16 var1, Word16 var2);    /* Short add,           1   */
Word16 sub (Word16 var1, Word16 var2);    /* Short sub,           1   */
Word16 abs_s (Word16 var1);               /* Short abs,           1   */
Word16 shl (Word16 var1, Word16 var2);    /* Short shift left,    1   */
Word16 shr (Word16 var1, Word16 var2);    /* Short shift right,   1   */
Word16 mult (Word16 var1, Word16 var2);   /* Short mult,          1   */
Word32 L_mult (Word16 var1, Word16 var2); /* Long mult,           1   */
Word32 Q0_mult (Word16 var1, Word16 var2);/* Long mult no shift   1   */
Word32 L_Q0mac (Word32 L_var3, Word16 var1, Word16 var2);
Word16 negate (Word16 var1);              /* Short negate,        1   */
Word16 extract_h (Word32 L_var1);         /* Extract high,        1   */
Word16 extract_l (Word32 L_var1);         /* Extract low,         1   */
Word16 round (Word32 L_var1);             /* Round,               1   */
Word32 L_mac (Word32 L_var3, Word16 var1, Word16 var2);   /* Mac,  1  */
Word32 L_msu (Word32 L_var3, Word16 var1, Word16 var2);   /* Msu,  1  */
Word32 L_macNs (Word32 L_var3, Word16 var1, Word16 var2); /* Mac without
                                                             sat, 1   */
Word32 L_msuNs (Word32 L_var3, Word16 var1, Word16 var2); /* Msu without
                                                             sat, 1   */
Word32 L_add (Word32 L_var1, Word32 L_var2);    /* Long add,        2 */
Word32 L_sub (Word32 L_var1, Word32 L_var2);    /* Long sub,        2 */
Word32 L_add_c (Word32 L_var1, Word32 L_var2);  /* Long add with c, 2 */
Word32 L_sub_c (Word32 L_var1, Word32 L_var2);  /* Long sub with c, 2 */
Word32 L_negate (Word32 L_var1);                /* Long negate,     2 */
Word16 mult_r (Word16 var1, Word16 var2);       /* Mult with round, 2 */
Word32 L_shl (Word32 L_var1, Word16 var2);      /* Long shift left, 2 */
Word32 L_shr (Word32 L_var1, Word16 var2);      /* Long shift right, 2*/
UWord32 LU_shl (UWord32 L_var1, Word16 var2);
UWord32 LU_shr (UWord32 L_var1, Word16 var2);
Word16 shr_r (Word16 var1, Word16 var2);        /* Shift right with
                                                   round, 2           */
Word16 mac_r (Word32 L_var3, Word16 var1, Word16 var2); /* Mac with
                                                           rounding,2 */
Word16 msu_r (Word32 L_var3, Word16 var1, Word16 var2); /* Msu with
                                                           rounding,2 */
Word32 L_deposit_h (Word16 var1);        /* 16 bit var1 -> MSB,     2 */
Word32 L_deposit_l (Word16 var1);        /* 16 bit var1 -> LSB,     2 */

Word32 L_shr_r (Word32 L_var1, Word16 var2); /* Long shift right with
                                                round,  3             */
Word32 L_abs (Word32 L_var1);            /* Long abs,              3  */
Word32 L_sat (Word32 L_var1);            /* Long saturation,       4  */
Word16 norm_s (Word16 var1);             /* Short norm,           15  */
Word16 div_s (Word16 var1, Word16 var2); /* Short division,       18  */
Word16 norm_l (Word32 L_var1);           /* Long norm,            30  */   

/*___________________________________________________________________________
 |                                                                           |
 |   Functions                                                               |
 |___________________________________________________________________________|
*/

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : saturate                                                |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Limit the 32 bit input to the range of a 16 bit word.                  |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    L_var1                                                                 |
 |             32 bit long signed integer (Word32) whose value falls in the  |
 |             range : 0x8000 0000 <= L_var1 <= 0x7fff ffff.                 |
 |                                                                           |
 |   Outputs :                                                               |
 |                                                                           |
 |    none                                                                   |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    var_out                                                                |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var_out <= 0x0000 7fff.                |
 |___________________________________________________________________________|
*/
 __inline Word16 
saturate (Word32 L_var1)
{
    Word16 var_out;

    if (L_var1 > 0X00007fffL)
    {
        Overflow = 1;
        var_out = MAX_16;
    }
    else if (L_var1 < (Word32) 0xffff8000L)
    {
        Overflow = 1;
        var_out = MIN_16;
    }
    else
    {
        Overflow = 0;
        var_out = extract_l (L_var1);
    }

    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : add                                                     |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Performs the addition (var1+var2) with overflow control and saturation;|
 |    the 16 bit result is set at +32767 when overflow occurs or at -32768   |
 |    when underflow occurs.                                                 |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    var1                                                                   |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var1 <= 0x0000 7fff.                   |
 |                                                                           |
 |    var2                                                                   |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var1 <= 0x0000 7fff.                   |
 |                                                                           |
 |   Outputs :                                                               |
 |                                                                           |
 |    none                                                                   |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    var_out                                                                |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var_out <= 0x0000 7fff.                |
 |___________________________________________________________________________|
*/ __inline 

Word16 add (Word16 var1, Word16 var2)
{
    Word16 var_out;
    Word32 L_sum;

    L_sum = (Word32) var1 + var2;
    var_out = saturate (L_sum);
    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : sub                                                     |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Performs the subtraction (var1+var2) with overflow control and satu-   |
 |    ration; the 16 bit result is set at +32767 when overflow occurs or at  |
 |    -32768 when underflow occurs.                                          |
 |                                                                           |
 |   Complexity weight : 1                                                   |
 |                                                                           |
 |   Inputs :                                                                |
 |                                                                           |
 |    var1                                                                   |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var1 <= 0x0000 7fff.                   |
 |                                                                           |
 |    var2                                                                   |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var1 <= 0x0000 7fff.                   |
 |                                                                           |
 |   Outputs :                                                               |
 |                                                                           |
 |    none                                                                   |
 |                                                                           |
 |   Return Value :                                                          |
 |                                                                           |
 |    var_out                                                                |
 |             16 bit short signed integer (Word16) whose value falls in the |
 |             range : 0xffff 8000 <= var_out <= 0x0000 7fff.                |
 |___________________________________________________________________________|
*/ __inline 

Word16 sub (Word16 var1, Word16 var2)
{
    Word16 var_out;
    Word32 L_diff;

    L_diff = (Word32) var1 - var2;
    var_out = saturate (L_diff);
    return (var_out);
}

/*___________________________________________________________________________
 |                                                                           |
 |   Function Name : abs_s                                                   |
 |                                                                           |
 |   Purpose :                                                               |
 |                                                                           |
 |    Absolute value of var1; abs_s(-32768) = 32767.                         |