diff options
| -rw-r--r-- | backends/midi/mt32/synth.cpp | 144 |
1 files changed, 58 insertions, 86 deletions
diff --git a/backends/midi/mt32/synth.cpp b/backends/midi/mt32/synth.cpp index 084919437d..7e617e2dc5 100644 --- a/backends/midi/mt32/synth.cpp +++ b/backends/midi/mt32/synth.cpp @@ -124,92 +124,67 @@ void prewarp(double *a0, double *a1, double *a2, double fc, double fs) { *a1 = (*a1) / wp; } -/* - * ---------------------------------------------------------- - * bilinear() - * - * Transform the numerator and denominator coefficients - * of s-domain biquad section into corresponding - * z-domain coefficients. +/** + * Transform the numerator and denominator coefficients of s-domain biquad + * section into corresponding z-domain coefficients. * - * Store the 4 IIR coefficients in array pointed by coef - * in following order: - * beta1, beta2 (denominator) - * alpha1, alpha2 (numerator) + * Store the 4 IIR coefficients in array pointed by coef in following order: + * beta1, beta2 (denominator) + * alpha1, alpha2 (numerator) * - * Arguments: - * a0-a2 - s-domain numerator coefficients - * b0-b2 - s-domain denominator coefficients - * k - filter gain factor. initially set to 1 - * and modified by each biquad section in such - * a way, as to make it the coefficient by - * which to multiply the overall filter gain - * in order to achieve a desired overall filter gain, - * specified in initial value of k. - * fs - sampling rate (Hz) - * coef - array of z-domain coefficients to be filled in. + * @param a0-a2 s-domain numerator coefficients + * @param b0-b2 s-domain denominator coefficients + * @param k filter gain factor. initially set to 1 and modified by each + * biquad section in such a way, as to make it the coefficient by + * which to multiply the overall filter gain in order to achieve a + * desired overall filter gain, specified in initial value of k. + * @param fs sampling rate (Hz) + * @param coef array of z-domain coefficients to be filled in. * - * Return: - * On return, set coef z-domain coefficients - * ---------------------------------------------------------- + * @returns On return, set coef z-domain coefficients */ -void bilinear( - double a0, double a1, double a2, /* numerator coefficients */ - double b0, double b1, double b2, /* denominator coefficients */ - double *k, /* overall gain factor */ - double fs, /* sampling rate */ - float *coef /* pointer to 4 iir coefficients */ -) -{ - double ad, bd; - - /* alpha (Numerator in s-domain) */ - ad = 4. * a2 * fs * fs + 2. * a1 * fs + a0; - /* beta (Denominator in s-domain) */ - bd = 4. * b2 * fs * fs + 2. * b1* fs + b0; - - /* update gain constant for this section */ - *k *= ad/bd; - - /* Denominator */ - *coef++ = (2. * b0 - 8. * b2 * fs * fs) - / bd; /* beta1 */ - *coef++ = (4. * b2 * fs * fs - 2. * b1 * fs + b0) - / bd; /* beta2 */ - - /* Nominator */ - *coef++ = (2. * a0 - 8. * a2 * fs * fs) - / ad; /* alpha1 */ - *coef = (4. * a2 * fs * fs - 2. * a1 * fs + a0) - / ad; /* alpha2 */ -} -void szxform( - double *a0, double *a1, double *a2, /* numerator coefficients */ - double *b0, double *b1, double *b2, /* denominator coefficients */ - double fc, /* Filter cutoff frequency */ - double fs, /* sampling rate */ - double *k, /* overall gain factor */ - float *coef) /* pointer to 4 iir coefficients */ -{ - /* Calculate a1 and a2 and overwrite the original values */ - prewarp(a0, a1, a2, fc, fs); - prewarp(b0, b1, b2, fc, fs); - bilinear(*a0, *a1, *a2, *b0, *b1, *b2, k, fs, coef); +void bilinear(double a0, double a1, double a2, double b0, double b1, double b2, double *k, double fs, float *coef) { + double ad, bd; + + // alpha (Numerator in s-domain) + ad = 4. * a2 * fs * fs + 2. * a1 * fs + a0; + // beta (Denominator in s-domain) + bd = 4. * b2 * fs * fs + 2. * b1 * fs + b0; + + // update gain constant for this section + *k *= ad / bd; + + // Denominator + *coef++ = (2. * b0 - 8. * b2 * fs * fs) / bd; // beta1 + *coef++ = (4. * b2 * fs * fs - 2. * b1 * fs + b0) / bd; // beta2 + + // Nominator + *coef++ = (2. * a0 - 8. * a2 * fs * fs) / ad; // alpha1 + *coef = (4. * a2 * fs * fs - 2. * a1 * fs + a0) / ad; // alpha2 } +/** + * @param a0-a2 numerator coefficients + * @param b0-b2 denominator coefficients + * @param fc filter cutoff frequency + * @param fs sampling rate + * @param coef pointer to 4 iir coefficients + */ +void szxform(double *a0, double *a1, double *a2, double *b0, double *b1, double *b2, double fc, double fs, double *k, float *coef) { + // Calculate a1 and a2 and overwrite the original values + prewarp(a0, a1, a2, fc, fs); + prewarp(b0, b1, b2, fc, fs); + bilinear(*a0, *a1, *a2, *b0, *b1, *b2, k, fs, coef); +} #ifdef HAVE_X86 #if defined(WIN32) && !(defined(__CYGWIN__) || defined(__MINGW32__)) -bool DetectSIMD() -{ - - bool found_simd; - _asm - - { +bool DetectSIMD() { + bool found_simd = false; + _asm { pushfd pop eax // get EFLAGS into eax mov ebx,eax // keep a copy @@ -238,15 +213,15 @@ bool DetectSIMD() jmp DONE NO_SIMD: mov found_simd,0 - DONE: +DONE: } return found_simd; - } bool Detect3DNow() { bool found3D = false; + __asm { pushfd pop eax @@ -271,17 +246,16 @@ bool Detect3DNow() { jz NO_3DNOW mov found3D, 1 NO_3DNOW: - } + return found3D; } #else -bool DetectSIMD() -{ +bool DetectSIMD() { return atti386_DetectSIMD(); } -bool Detect3DNow() -{ + +bool Detect3DNow() { return atti386_Detect3DNow(); } #endif @@ -289,9 +263,9 @@ bool Detect3DNow() #ifdef NOMANSLAND -//#define SETRATE 32000 +// #define SETRATE 32000 #define SETRATE myProp.SampleRate -//#define SETRATE 44100 +// #define SETRATE 44100 // Used to regenerate waveform file after sampling rate change #define MAKEWAVES 0 @@ -308,8 +282,6 @@ bool Detect3DNow() #define MONITORPARTIALS 1 // Dump syx file of temp tibres right before reset #define SAVECUSTOM 0 - - // Constant tuning for now #define TUNING 440.0 @@ -338,7 +310,7 @@ bool Detect3DNow() #define REV_PLATET60 ( REV_PLATESIZE * REV_PLATESIZE * REV_PLATESIZE ) / 7 #define REV_TAPT60 ( REV_TAPSIZE * REV_TAPSIZE * REV_TAPSIZE ) / 1 -//#define HLRATIO 2.0f +// #define HLRATIO 2.0f #define SYSEX_SIZE 512 |