Avoid some more explicit loops in the filters

Alc/filters/filter.cpp

@@ -92,14 +92,13 @@ void BiquadFilter_setParams(BiquadFilter *filter, BiquadType type, ALfloat gain,
 
 void BiquadFilter_processC(BiquadFilter *filter, ALfloat *RESTRICT dst, const ALfloat *RESTRICT src, ALsizei numsamples)
 {
-    const ALfloat a1 = filter->a1;
-    const ALfloat a2 = filter->a2;
     const ALfloat b0 = filter->b0;
     const ALfloat b1 = filter->b1;
     const ALfloat b2 = filter->b2;
+    const ALfloat a1 = filter->a1;
+    const ALfloat a2 = filter->a2;
     ALfloat z1 = filter->z1;
     ALfloat z2 = filter->z2;
-    ALsizei i;
 
     ASSUME(numsamples > 0);
 
@@ -111,14 +110,14 @@ void BiquadFilter_processC(BiquadFilter *filter, ALfloat *RESTRICT dst, const AL
      *
      * See: http://www.earlevel.com/main/2003/02/28/biquads/
      */
-    for(i = 0;i < numsamples;i++)
+    auto proc_sample = [b0,b1,b2,a1,a2,&z1,&z2](ALfloat input) noexcept -> ALfloat
     {
-        ALfloat input = src[i];
         ALfloat output = input*b0 + z1;
         z1 = input*b1 - output*a1 + z2;
         z2 = input*b2 - output*a2;
-        dst[i] = output;
-    }
+        return output;
+    };
+    std::transform<const ALfloat*RESTRICT>(src, src+numsamples, dst, proc_sample);
 
     filter->z1 = z1;
     filter->z2 = z2;

Alc/filters/nfc.cpp

@@ -2,6 +2,9 @@
 #include "config.h"
 
 #include "nfc.h"
+
+#include <algorithm>
+
 #include "alMain.h"
 
 #include <string.h>
@@ -228,18 +231,17 @@ void NfcFilterProcess1(NfcFilter *nfc, float *RESTRICT dst, const float *RESTRIC
     const float b1 = nfc->first.b1;
     const float a1 = nfc->first.a1;
     float z1 = nfc->first.z[0];
-    int i;
 
     ASSUME(count > 0);
 
-    for(i = 0;i < count;i++)
+    auto proc_sample = [gain,b1,a1,&z1](float in) noexcept -> float
     {
-        float y = src[i]*gain - a1*z1;
+        float y = in*gain - a1*z1;
         float out = y + b1*z1;
         z1 += y;
-
-        dst[i] = out;
-    }
+        return out;
+    };
+    std::transform<const float*RESTRICT>(src, src+count, dst, proc_sample);
     nfc->first.z[0] = z1;
 }
 
@@ -252,19 +254,18 @@ void NfcFilterProcess2(NfcFilter *nfc, float *RESTRICT dst, const float *RESTRIC
     const float a2 = nfc->second.a2;
     float z1 = nfc->second.z[0];
     float z2 = nfc->second.z[1];
-    int i;
 
     ASSUME(count > 0);
 
-    for(i = 0;i < count;i++)
+    auto proc_sample = [gain,b1,b2,a1,a2,&z1,&z2](float in) noexcept -> float
     {
-        float y = src[i]*gain - a1*z1 - a2*z2;
+        float y = in*gain - a1*z1 - a2*z2;
         float out = y + b1*z1 + b2*z2;
         z2 += z1;
         z1 += y;
-
-        dst[i] = out;
-    }
+        return out;
+    };
+    std::transform<const float*RESTRICT>(src, src+count, dst, proc_sample);
     nfc->second.z[0] = z1;
     nfc->second.z[1] = z2;
 }
@@ -281,13 +282,12 @@ void NfcFilterProcess3(NfcFilter *nfc, float *RESTRICT dst, const float *RESTRIC
     float z1 = nfc->third.z[0];
     float z2 = nfc->third.z[1];
     float z3 = nfc->third.z[2];
-    int i;
 
     ASSUME(count > 0);
 
-    for(i = 0;i < count;i++)
+    auto proc_sample = [gain,b1,b2,b3,a1,a2,a3,&z1,&z2,&z3](float in) noexcept -> float
     {
-        float y = src[i]*gain - a1*z1 - a2*z2;
+        float y = in*gain - a1*z1 - a2*z2;
         float out = y + b1*z1 + b2*z2;
         z2 += z1;
         z1 += y;
@@ -296,8 +296,9 @@ void NfcFilterProcess3(NfcFilter *nfc, float *RESTRICT dst, const float *RESTRIC
         out = y + b3*z3;
         z3 += y;
 
-        dst[i] = out;
-    }
+        return out;
+    };
+    std::transform<const float*RESTRICT>(src, src+count, dst, proc_sample);
     nfc->third.z[0] = z1;
     nfc->third.z[1] = z2;
     nfc->third.z[2] = z3;

Alc/filters/splitter.cpp

@@ -3,15 +3,18 @@
 
 #include "splitter.h"
 
+#include <cmath>
+#include <algorithm>
+
 #include "math_defs.h"
 
 
 void bandsplit_init(BandSplitter *splitter, ALfloat f0norm)
 {
     ALfloat w = f0norm * F_TAU;
-    ALfloat cw = cosf(w);
+    ALfloat cw = std::cos(w);
     if(cw > FLT_EPSILON)
-        splitter->coeff = (sinf(w) - 1.0f) / cw;
+        splitter->coeff = (std::sin(w) - 1.0f) / cw;
     else
         splitter->coeff = cw * -0.5f;
 
@@ -30,51 +33,46 @@ void bandsplit_clear(BandSplitter *splitter)
 void bandsplit_process(BandSplitter *splitter, ALfloat *RESTRICT hpout, ALfloat *RESTRICT lpout,
                        const ALfloat *input, ALsizei count)
 {
-    ALfloat lp_coeff, hp_coeff, lp_y, hp_y, d;
-    ALfloat lp_z1, lp_z2, hp_z1;
-    ALsizei i;
-
     ASSUME(count > 0);
 
-    hp_coeff = splitter->coeff;
-    lp_coeff = splitter->coeff*0.5f + 0.5f;
-    lp_z1 = splitter->lp_z1;
-    lp_z2 = splitter->lp_z2;
-    hp_z1 = splitter->hp_z1;
-    for(i = 0;i < count;i++)
+    const float ap_coeff{splitter->coeff};
+    const float lp_coeff{splitter->coeff*0.5f + 0.5f};
+    float lp_z1{splitter->lp_z1};
+    float lp_z2{splitter->lp_z2};
+    float ap_z1{splitter->hp_z1};
+    auto proc_sample = [ap_coeff,lp_coeff,&lp_z1,&lp_z2,&ap_z1,&lpout](const float in) noexcept -> float
     {
-        ALfloat in = input[i];
-
         /* Low-pass sample processing. */
-        d = (in - lp_z1) * lp_coeff;
-        lp_y = lp_z1 + d;
+        float d{(in - lp_z1) * lp_coeff};
+        float lp_y{lp_z1 + d};
         lp_z1 = lp_y + d;
 
         d = (lp_y - lp_z2) * lp_coeff;
         lp_y = lp_z2 + d;
         lp_z2 = lp_y + d;
 
-        lpout[i] = lp_y;
+        *(lpout++) = lp_y;
 
         /* All-pass sample processing. */
-        hp_y = in*hp_coeff + hp_z1;
-        hp_z1 = in - hp_y*hp_coeff;
+        float ap_y{in*ap_coeff + ap_z1};
+        ap_z1 = in - ap_y*ap_coeff;
 
         /* High-pass generated from removing low-passed output. */
-        hpout[i] = hp_y - lp_y;
-    }
+        return ap_y - lp_y;
+    };
+    std::transform<const float*RESTRICT>(input, input+count, hpout, proc_sample);
     splitter->lp_z1 = lp_z1;
     splitter->lp_z2 = lp_z2;
-    splitter->hp_z1 = hp_z1;
+    splitter->hp_z1 = ap_z1;
 }
 
 
 void splitterap_init(SplitterAllpass *splitter, ALfloat f0norm)
 {
     ALfloat w = f0norm * F_TAU;
-    ALfloat cw = cosf(w);
+    ALfloat cw = std::cos(w);
     if(cw > FLT_EPSILON)
-        splitter->coeff = (sinf(w) - 1.0f) / cw;
+        splitter->coeff = (std::sin(w) - 1.0f) / cw;
     else
         splitter->coeff = cw * -0.5f;
 
@@ -88,22 +86,16 @@ void splitterap_clear(SplitterAllpass *splitter)
 
 void splitterap_process(SplitterAllpass *splitter, ALfloat *RESTRICT samples, ALsizei count)
 {
-    ALfloat coeff, in, out;
-    ALfloat z1;
-    ALsizei i;
-
     ASSUME(count > 0);
 
-    coeff = splitter->coeff;
-    z1 = splitter->z1;
-    for(i = 0;i < count;i++)
+    const float coeff{splitter->coeff};
+    float z1{splitter->z1};
+    auto proc_sample = [coeff,&z1](const float in) noexcept -> float
     {
-        in = samples[i];
-
-        out = in*coeff + z1;
+        float out{in*coeff + z1};
         z1 = in - out*coeff;
-
-        samples[i] = out;
-    }
+        return out;
+    };
+    std::transform(samples, samples+count, samples, proc_sample);
     splitter->z1 = z1;
 }