Diff: DSP/source/BasicMathFunctions/arm_scale_f32.c

Revision:

0:eedb7d567a5d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/DSP/source/BasicMathFunctions/arm_scale_f32.c	Thu Apr 12 01:31:58 2018 +0000
@@ -0,0 +1,158 @@
+/* ----------------------------------------------------------------------
+ * Project:      CMSIS DSP Library
+ * Title:        arm_scale_f32.c
+ * Description:  Multiplies a floating-point vector by a scalar
+ *
+ * $Date:        27. January 2017
+ * $Revision:    V.1.5.1
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "arm_math.h"
+
+/**
+ * @ingroup groupMath
+ */
+
+/**
+ * @defgroup scale Vector Scale
+ *
+ * Multiply a vector by a scalar value.  For floating-point data, the algorithm used is:
+ *
+ * <pre>
+ *     pDst[n] = pSrc[n] * scale,   0 <= n < blockSize.
+ * </pre>
+ *
+ * In the fixed-point Q7, Q15, and Q31 functions, <code>scale</code> is represented by
+ * a fractional multiplication <code>scaleFract</code> and an arithmetic shift <code>shift</code>.
+ * The shift allows the gain of the scaling operation to exceed 1.0.
+ * The algorithm used with fixed-point data is:
+ *
+ * <pre>
+ *     pDst[n] = (pSrc[n] * scaleFract) << shift,   0 <= n < blockSize.
+ * </pre>
+ *
+ * The overall scale factor applied to the fixed-point data is
+ * <pre>
+ *     scale = scaleFract * 2^shift.
+ * </pre>
+ *
+ * The functions support in-place computation allowing the source and destination
+ * pointers to reference the same memory buffer.
+ */
+
+/**
+ * @addtogroup scale
+ * @{
+ */
+
+/**
+ * @brief Multiplies a floating-point vector by a scalar.
+ * @param[in]       *pSrc points to the input vector
+ * @param[in]       scale scale factor to be applied
+ * @param[out]      *pDst points to the output vector
+ * @param[in]       blockSize number of samples in the vector
+ * @return none.
+ */
+
+
+void arm_scale_f32(
+  float32_t * pSrc,
+  float32_t scale,
+  float32_t * pDst,
+  uint32_t blockSize)
+{
+  uint32_t blkCnt;                               /* loop counter */
+#if defined (ARM_MATH_DSP)
+
+/* Run the below code for Cortex-M4 and Cortex-M3 */
+  float32_t in1, in2, in3, in4;                  /* temporary variabels */
+
+  /*loop Unrolling */
+  blkCnt = blockSize >> 2U;
+
+  /* First part of the processing with loop unrolling.  Compute 4 outputs at a time.
+   ** a second loop below computes the remaining 1 to 3 samples. */
+  while (blkCnt > 0U)
+  {
+    /* C = A * scale */
+    /* Scale the input and then store the results in the destination buffer. */
+    /* read input samples from source */
+    in1 = *pSrc;
+    in2 = *(pSrc + 1);
+
+    /* multiply with scaling factor */
+    in1 = in1 * scale;
+
+    /* read input sample from source */
+    in3 = *(pSrc + 2);
+
+    /* multiply with scaling factor */
+    in2 = in2 * scale;
+
+    /* read input sample from source */
+    in4 = *(pSrc + 3);
+
+    /* multiply with scaling factor */
+    in3 = in3 * scale;
+    in4 = in4 * scale;
+    /* store the result to destination */
+    *pDst = in1;
+    *(pDst + 1) = in2;
+    *(pDst + 2) = in3;
+    *(pDst + 3) = in4;
+
+    /* update pointers to process next samples */
+    pSrc += 4U;
+    pDst += 4U;
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+
+  /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
+   ** No loop unrolling is used. */
+  blkCnt = blockSize % 0x4U;
+
+#else
+
+  /* Run the below code for Cortex-M0 */
+
+  /* Initialize blkCnt with number of samples */
+  blkCnt = blockSize;
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+  while (blkCnt > 0U)
+  {
+    /* C = A * scale */
+    /* Scale the input and then store the result in the destination buffer. */
+    *pDst++ = (*pSrc++) * scale;
+
+    /* Decrement the loop counter */
+    blkCnt--;
+  }
+}
+
+/**
+ * @} end of scale group
+ */
+