example6_acc_dsp.c

MATLAB仿真技术与应用一书的配套光盘

/*
 * example6_acc_dsp.c
 *
 * DSP Blockset function calls
 * Real-Time Workshop code generation for Simulink model "example6_acc.mdl".
 *
 * Model Version                        : 1.42
 * Real-Time Workshop file version      : 4.1 $Date: 2001/05/16 13:59:43 $
 * Real-Time Workshop file generated on : Sun May 18 17:35:27 2003
 * TLC version                          : 4.1 (May 19 2001)
 * C source code generated on           : Sun May 18 17:35:27 2003
 *
 * Relevant TLC Options:
 *   InlineParameters      = 0
 *   RollThreshold         = 5
 *   CodeFormat            = S-Function
 *
 * Simulink model settings:
 *   Solver     : VariableStep
 *   StartTime  : 0.0 s
 *   StopTime   : 10.0 s
 *   Variable step solver used
 */

#include "example6_acc_dsp.h"

/* Function: DSP_InitializeSeed
 *  Bit-shift the given initial seed
 */
extern void DSP_InitializeSeed(uint32_T *urandSeed, real_T initSeed)
{
  const uint32_T maxseed = 2147483646; /* 2^31-2 */
  const uint32_T seed0 = 1144108930;    /* Seed #6, starting from seed = 1 */
  const uint32_T bit16 = 32768;         /* 2^15   */

  *urandSeed = (uint32_T)initSeed;

  /* Interchange bits 1-15 and 17-31 */
  {
    int_T r = *urandSeed >> 16;
    int_T t = *urandSeed & bit16;
    *urandSeed = ((*urandSeed - (r << 16) - t) << 16) + t + r;
  }
  if (*urandSeed < 1) {
    *urandSeed = seed0;
  }
  if (*urandSeed > maxseed) {
    *urandSeed = maxseed;
  }
}                                       /* end DSP_InitializeSeed */

/*
 * DSP Blockset Random Source block
 * Uniform random number generator
 * Generates random number in range (0,1)
 */
extern real_T DSP_UniformRand(uint32_T *seed) /* pointer to a running seed */
{
  const uint32_T IA = 16807;            /* magic multiplier = 7^5    */
  const uint32_T IM = 2147483647;       /* modulus = 2^31-1            */
  const uint32_T IQ = 127773;           /* IM div IA                */
  const uint32_T IR = 2836;             /* IM modulo IA                */
  const real_T S = 4.656612875245797e-10; /* reciprocal of 2^31-1    */

  uint32_T hi = *seed / IQ;
  uint32_T lo = *seed % IQ;
  int32_T test = IA * lo - IR * hi;     /* never overflows */

  *seed = ((test < 0) ? (unsigned int)(test + IM) : (unsigned int)test);

  return( (real_T) ((*seed) * S) );
}                                       /* end DSP_UniformRand */

/* Function: DSP_NormalRand 
 *  Normal (Gaussian) random number generator 
 */
extern real_T DSP_NormalRand(unsigned int *seed)
{
  real_T sr, si, t;
  do {
    sr = 2.0 * DSP_UniformRand(seed) - 1.0;
    si = 2.0 * DSP_UniformRand(seed) - 1.0;
    t = sr * sr + si * si;
  } while (t > 1.0);

  return(sr * sqrt((-2.0 * log(t)) / t));
}                                       /* end DSP_NormalRand */