CMSIS-NN: Added arm_softmax_with_batch_q7

Some study of the error rate of softmax compared to f32 reference.

Testing/Source/Softmax.cpp

@@ -5,6 +5,31 @@
 
 #include <cstdio>
 
+/*
+
+Tests have shown that, compared to a float32 implementation
+there is an average error of 4.2 percent and standard deviation
+of 0.89.
+
+Which means that with 100 batches, 4 batches will give the wrong position
+for the max.
+
+But it depends highly of the vector dimension.
+
+Regressions are giving:
+
+Average error rate = -0.555548 + 0.246918 vecDim
+Variance = -0.0112281 + 0.0382476 vecDim
+
+So for vecDim = 21 we have
+Average error rate = 4.6 percent
+Variance for error rate = 0.8
+
+This data is used to define the threshold for tests
+
+*/
+#define THRESHOLD 7.5
+
 int16_t findMaxIndex(q7_t *vec_in, int length)
 {
   int16_t currentIndex=0;
@@ -61,9 +86,30 @@ int16_t differences(int16_t *pa,int16_t *pb, int length)
        }
 
        int diff = differences(ref.ptr(),output.ptr(),this->nbSamples);
-       //printf("diffs = %d\n",diff);
-       // 6% of errors are accepted for 20 entry samples
-       ASSERT_TRUE(100.0*diff/this->nbSamples <= 6.5);
+       
+       ASSERT_TRUE(100.0*diff/this->nbSamples <= THRESHOLD);
+       
+    } 
+
+    void Softmax::test_softmax_with_batch_q7()
+    {
+       const q7_t *vec_in = input.ptr();
+       q7_t *pTmp = temp.ptr();
+       int16_t *pOut = output.ptr();
+       int16_t maxIndex;
+
+       arm_softmax_with_batch_q7(vec_in, this->nbSamples,this->vecDim, pTmp );
+
+       for(int i=0; i <this->nbSamples;i++)
+       {
+          maxIndex=findMaxIndex(pTmp,this->vecDim);
+          *pOut++ = maxIndex;
+          pTmp += this->vecDim;
+       }
+
+       int diff = differences(ref.ptr(),output.ptr(),this->nbSamples);
+       
+       ASSERT_TRUE(100.0*diff/this->nbSamples <= THRESHOLD);
        
     } 
 
@@ -74,6 +120,7 @@ int16_t differences(int16_t *pa,int16_t *pb, int length)
        switch(id)
        {
           case Softmax::TEST_SOFTMAX_Q7_1:
+          {
                ref.reload(Softmax::REF1_S16_ID,mgr);
                dims.reload(Softmax::DIMS1_S16_ID,mgr);
                input.reload(Softmax::INPUT1_Q7_ID,mgr);
@@ -82,6 +129,20 @@ int16_t differences(int16_t *pa,int16_t *pb, int length)
 
                this->nbSamples = pDims[0];
                this->vecDim = pDims[1];
+          }
+          break; 
+          
+          case Softmax::TEST_SOFTMAX_WITH_BATCH_Q7_2:
+          {
+               ref.reload(Softmax::REF1_S16_ID,mgr);
+               dims.reload(Softmax::DIMS1_S16_ID,mgr);
+               input.reload(Softmax::INPUT1_Q7_ID,mgr);
+
+               const int16_t *pDims=dims.ptr();
+
+               this->nbSamples = pDims[0];
+               this->vecDim = pDims[1];
+          }
           break; 
 
        }

Testing/desc.txt

@@ -656,6 +656,7 @@ group Root {
 
           Functions {
             arm_softmax_q7 Test 1:test_softmax_q7
+            arm_softmax_with_batch_q7 Test 2:test_softmax_with_batch_q7
           }
        }
     }