dsp_fltoq15.h64

来自「dm642函数库」· H64 代码 · 共 124 行

;* ======================================================================== *;
;*  TEXAS INSTRUMENTS, INC.                                                 *;
;*                                                                          *;
;*  DSPLIB  DSP Signal Processing Library                                   *;
;*                                                                          *;
;*      Release:        Revision 1.04b                                      *;
;*      CVS Revision:   1.9     Thu Oct  3 11:08:07 2002 (UTC)              *;
;*      Snapshot date:  23-Oct-2003                                         *;
;*                                                                          *;
;*  This library contains proprietary intellectual property of Texas        *;
;*  Instruments, Inc.  The library and its source code are protected by     *;
;*  various copyrights, and portions may also be protected by patents or    *;
;*  other legal protections.                                                *;
;*                                                                          *;
;*  This software is licensed for use with Texas Instruments TMS320         *;
;*  family DSPs.  This license was provided to you prior to installing      *;
;*  the software.  You may review this license by consulting the file       *;
;*  TI_license.PDF which accompanies the files in this library.             *;
;* ------------------------------------------------------------------------ *;
;*          Copyright (C) 2003 Texas Instruments, Incorporated.             *;
;*                          All Rights Reserved.                            *;
;* ======================================================================== *;
;* ======================================================================== *;
;*  Assembler compatibility shim for assembling 4.30 and later code on      *;
;*  tools prior to 4.30.                                                    *;
;* ======================================================================== *;
;* ======================================================================== *;
;*  End of assembler compatibility shim.                                    *;
;* ======================================================================== *;
* ========================================================================= *
*                                                                           *
*     TEXAS INSTRUMENTS, INC.                                               *
*                                                                           *
*     NAME                                                                  *
*           DSP_fltoq15                                                     *
*                                                                           *
*     REVISION DATE                                                         *
*         03-Oct-2002                                                       *
*                                                                           *
*   USAGE                                                                   *
*       This routine is C-callable and can be called as:                    *
*                                                                           *
*       void DSP_fltoq15(float x[], short r[], short nx)                    *
*                                                                           *
*       x[nx] : Pointer to values of type float                             *
*       r[nx] : Contains Q15 values from x[nx]                              *
*       nx    : Number of elements in arrays                                *
*                                                                           *
*   DESCRIPTION                                                             *
*       Convert the IEEE floating point numbers stored in vector x[] into   *
*       Q.15 format numbers stored in vector r[]. Results are truncated     *
*       towards zero. Values that exceed the size limit will be saturated   *
*       to 0x7fff if value is positive and 0x8000 if value is negative.     *
*       All values too small to be correctly represented will be truncated  *
*       to 0.                                                               *
*                                                                           *
*       The 16-bit Q.15 format is defined as follows:                       *
*                                                                           *
*           1 11111                                                         *
*           5 432109876543210                                               *
*           S.XXXXXXXXXXXXXXX                                               *
*                                                                           *
*           range: 1.000000000000000 = -1.0               <-> -32768        *
*                  0.111111111111111 =  0.999969482421875 <->  32767        *
*                                                                           *
*       IEEE floating point format is defined as follows:                   *
*                                                                           *
*           31 30....23  22.....0                                           *
*            S EXPONENT  MANTISSA                                           *
*                                                                           *
*       The value is obtained as: (-1)^S * 1.MANTISSA * 2^(EXPONENT-127)    *
*                                                                           *
*     C CODE                                                                *
*         void DSP_fltoq15(float x[], short r[], short nx)                  *
*         {                                                                 *
*             int i, a;                                                     *
*                                                                           *
*             for(i = 0; i < nx; i++)                                       *
*             {                                                             *
*                 a = 32768 * x[i];                                         *
*                                                                           *
*                 // saturate to 16-bit //                                  *
*                 if (a>32767)  a =  32767;                                 *
*                 if (a<-32768) a = -32768;                                 *
*                                                                           *
*                 r[i] = (short) a;                                         *
*             }                                                             *
*         }                                                                 *
*                                                                           *
*     ASSUMPTIONS                                                           *
*         1.  nx >= 2                                                       *
*         2.  nx is a multiple of 2                                         *
*                                                                           *
*     NOTES                                                                 *
*         This code is interrupt-tolerant but not interruptible.            *
*         This implementation is ENDIAN NEUTRAL.                            *
*                                                                           *
*     TECHNIQUE                                                             *
*         Loop is unrolled twice.                                           *
*                                                                           *
*     CYCLES                                                                *
*         3 * nx/2 + 17                                                     *
*                                                                           *
*         This cycle count includes 6 cycles of function call overhead.     *
*         The exact overhead will vary depending on the compiler options    *
*         used.                                                             *
*                                                                           *
*     CODESIZE                                                              *
*         168 bytes                                                         *
*                                                                           *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2003 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *

        .global _DSP_fltoq15

* ========================================================================= *
*   End of file:  dsp_fltoq15.h64                                           *
* ------------------------------------------------------------------------- *
*             Copyright (c) 2003 Texas Instruments, Incorporated.           *
*                            All Rights Reserved.                           *
* ========================================================================= *