| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010 ARM Limited. All rights reserved. |
| * |
| * $Date: 15. July 2011 |
| * $Revision: V1.0.10 |
| * |
| * Project: CMSIS DSP Library |
| * Title: arm_cos_f32.c |
| * |
| * Description: Fast cosine calculation for floating-point values. |
| * |
| * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0 |
| * |
| * Version 1.0.10 2011/7/15 |
| * Big Endian support added and Merged M0 and M3/M4 Source code. |
| * |
| * Version 1.0.3 2010/11/29 |
| * Re-organized the CMSIS folders and updated documentation. |
| * |
| * Version 1.0.2 2010/11/11 |
| * Documentation updated. |
| * |
| * Version 1.0.1 2010/10/05 |
| * Production release and review comments incorporated. |
| * |
| * Version 1.0.0 2010/09/20 |
| * Production release and review comments incorporated. |
| * -------------------------------------------------------------------- */ |
| |
| #include "arm_math.h" |
| /** |
| * @ingroup groupFastMath |
| */ |
| |
| /** |
| * @defgroup cos Cosine |
| * |
| * Computes the trigonometric cosine function using a combination of table lookup |
| * and cubic interpolation. There are separate functions for |
| * Q15, Q31, and floating-point data types. |
| * The input to the floating-point version is in radians while the |
| * fixed-point Q15 and Q31 have a scaled input with the range |
| * [0 1) mapping to [0 2*pi). |
| * |
| * The implementation is based on table lookup using 256 values together with cubic interpolation. |
| * The steps used are: |
| * -# Calculation of the nearest integer table index |
| * -# Fetch the four table values a, b, c, and d |
| * -# Compute the fractional portion (fract) of the table index. |
| * -# Calculation of wa, wb, wc, wd |
| * -# The final result equals <code>a*wa + b*wb + c*wc + d*wd</code> |
| * |
| * where |
| * <pre> |
| * a=Table[index-1]; |
| * b=Table[index+0]; |
| * c=Table[index+1]; |
| * d=Table[index+2]; |
| * </pre> |
| * and |
| * <pre> |
| * wa=-(1/6)*fract.^3 + (1/2)*fract.^2 - (1/3)*fract; |
| * wb=(1/2)*fract.^3 - fract.^2 - (1/2)*fract + 1; |
| * wc=-(1/2)*fract.^3+(1/2)*fract.^2+fract; |
| * wd=(1/6)*fract.^3 - (1/6)*fract; |
| * </pre> |
| */ |
| |
| /** |
| * @addtogroup cos |
| * @{ |
| */ |
| |
| |
| /** |
| * \par |
| * <b>Example code for Generation of Cos Table:</b> |
| * tableSize = 256; |
| * <pre>for(n = -1; n < (tableSize + 1); n++) |
| * { |
| * cosTable[n+1]= cos(2*pi*n/tableSize); |
| * } </pre> |
| * where pi value is 3.14159265358979 |
| */ |
| |
| static const float32_t cosTable[259] = { |
| 0.999698817729949950f, 1.000000000000000000f, 0.999698817729949950f, |
| 0.998795449733734130f, 0.997290432453155520f, 0.995184719562530520f, |
| 0.992479562759399410f, 0.989176511764526370f, |
| 0.985277652740478520f, 0.980785250663757320f, 0.975702106952667240f, |
| 0.970031261444091800f, 0.963776051998138430f, 0.956940352916717530f, |
| 0.949528157711029050f, 0.941544055938720700f, |
| 0.932992815971374510f, 0.923879504203796390f, 0.914209783077239990f, |
| 0.903989315032958980f, 0.893224298954010010f, 0.881921291351318360f, |
| 0.870086967945098880f, 0.857728600502014160f, |
| 0.844853579998016360f, 0.831469595432281490f, 0.817584812641143800f, |
| 0.803207516670227050f, 0.788346409797668460f, 0.773010432720184330f, |
| 0.757208824157714840f, 0.740951120853424070f, |
| 0.724247097969055180f, 0.707106769084930420f, 0.689540565013885500f, |
| 0.671558976173400880f, 0.653172850608825680f, 0.634393274784088130f, |
| 0.615231573581695560f, 0.595699310302734380f, |
| 0.575808167457580570f, 0.555570244789123540f, 0.534997642040252690f, |
| 0.514102756977081300f, 0.492898195981979370f, 0.471396744251251220f, |
| 0.449611335992813110f, 0.427555084228515630f, |
| 0.405241310596466060f, 0.382683426141738890f, 0.359895050525665280f, |
| 0.336889863014221190f, 0.313681751489639280f, 0.290284663438797000f, |
| 0.266712754964828490f, 0.242980182170867920f, |
| 0.219101235270500180f, 0.195090323686599730f, 0.170961886644363400f, |
| 0.146730467677116390f, 0.122410677373409270f, 0.098017141222953796f, |
| 0.073564566671848297f, 0.049067676067352295f, |
| 0.024541229009628296f, 0.000000000000000061f, -0.024541229009628296f, |
| -0.049067676067352295f, -0.073564566671848297f, -0.098017141222953796f, |
| -0.122410677373409270f, -0.146730467677116390f, |
| -0.170961886644363400f, -0.195090323686599730f, -0.219101235270500180f, |
| -0.242980182170867920f, -0.266712754964828490f, -0.290284663438797000f, |
| -0.313681751489639280f, -0.336889863014221190f, |
| -0.359895050525665280f, -0.382683426141738890f, -0.405241310596466060f, |
| -0.427555084228515630f, -0.449611335992813110f, -0.471396744251251220f, |
| -0.492898195981979370f, -0.514102756977081300f, |
| -0.534997642040252690f, -0.555570244789123540f, -0.575808167457580570f, |
| -0.595699310302734380f, -0.615231573581695560f, -0.634393274784088130f, |
| -0.653172850608825680f, -0.671558976173400880f, |
| -0.689540565013885500f, -0.707106769084930420f, -0.724247097969055180f, |
| -0.740951120853424070f, -0.757208824157714840f, -0.773010432720184330f, |
| -0.788346409797668460f, -0.803207516670227050f, |
| -0.817584812641143800f, -0.831469595432281490f, -0.844853579998016360f, |
| -0.857728600502014160f, -0.870086967945098880f, -0.881921291351318360f, |
| -0.893224298954010010f, -0.903989315032958980f, |
| -0.914209783077239990f, -0.923879504203796390f, -0.932992815971374510f, |
| -0.941544055938720700f, -0.949528157711029050f, -0.956940352916717530f, |
| -0.963776051998138430f, -0.970031261444091800f, |
| -0.975702106952667240f, -0.980785250663757320f, -0.985277652740478520f, |
| -0.989176511764526370f, -0.992479562759399410f, -0.995184719562530520f, |
| -0.997290432453155520f, -0.998795449733734130f, |
| -0.999698817729949950f, -1.000000000000000000f, -0.999698817729949950f, |
| -0.998795449733734130f, -0.997290432453155520f, -0.995184719562530520f, |
| -0.992479562759399410f, -0.989176511764526370f, |
| -0.985277652740478520f, -0.980785250663757320f, -0.975702106952667240f, |
| -0.970031261444091800f, -0.963776051998138430f, -0.956940352916717530f, |
| -0.949528157711029050f, -0.941544055938720700f, |
| -0.932992815971374510f, -0.923879504203796390f, -0.914209783077239990f, |
| -0.903989315032958980f, -0.893224298954010010f, -0.881921291351318360f, |
| -0.870086967945098880f, -0.857728600502014160f, |
| -0.844853579998016360f, -0.831469595432281490f, -0.817584812641143800f, |
| -0.803207516670227050f, -0.788346409797668460f, -0.773010432720184330f, |
| -0.757208824157714840f, -0.740951120853424070f, |
| -0.724247097969055180f, -0.707106769084930420f, -0.689540565013885500f, |
| -0.671558976173400880f, -0.653172850608825680f, -0.634393274784088130f, |
| -0.615231573581695560f, -0.595699310302734380f, |
| -0.575808167457580570f, -0.555570244789123540f, -0.534997642040252690f, |
| -0.514102756977081300f, -0.492898195981979370f, -0.471396744251251220f, |
| -0.449611335992813110f, -0.427555084228515630f, |
| -0.405241310596466060f, -0.382683426141738890f, -0.359895050525665280f, |
| -0.336889863014221190f, -0.313681751489639280f, -0.290284663438797000f, |
| -0.266712754964828490f, -0.242980182170867920f, |
| -0.219101235270500180f, -0.195090323686599730f, -0.170961886644363400f, |
| -0.146730467677116390f, -0.122410677373409270f, -0.098017141222953796f, |
| -0.073564566671848297f, -0.049067676067352295f, |
| -0.024541229009628296f, -0.000000000000000184f, 0.024541229009628296f, |
| 0.049067676067352295f, 0.073564566671848297f, 0.098017141222953796f, |
| 0.122410677373409270f, 0.146730467677116390f, |
| 0.170961886644363400f, 0.195090323686599730f, 0.219101235270500180f, |
| 0.242980182170867920f, 0.266712754964828490f, 0.290284663438797000f, |
| 0.313681751489639280f, 0.336889863014221190f, |
| 0.359895050525665280f, 0.382683426141738890f, 0.405241310596466060f, |
| 0.427555084228515630f, 0.449611335992813110f, 0.471396744251251220f, |
| 0.492898195981979370f, 0.514102756977081300f, |
| 0.534997642040252690f, 0.555570244789123540f, 0.575808167457580570f, |
| 0.595699310302734380f, 0.615231573581695560f, 0.634393274784088130f, |
| 0.653172850608825680f, 0.671558976173400880f, |
| 0.689540565013885500f, 0.707106769084930420f, 0.724247097969055180f, |
| 0.740951120853424070f, 0.757208824157714840f, 0.773010432720184330f, |
| 0.788346409797668460f, 0.803207516670227050f, |
| 0.817584812641143800f, 0.831469595432281490f, 0.844853579998016360f, |
| 0.857728600502014160f, 0.870086967945098880f, 0.881921291351318360f, |
| 0.893224298954010010f, 0.903989315032958980f, |
| 0.914209783077239990f, 0.923879504203796390f, 0.932992815971374510f, |
| 0.941544055938720700f, 0.949528157711029050f, 0.956940352916717530f, |
| 0.963776051998138430f, 0.970031261444091800f, |
| 0.975702106952667240f, 0.980785250663757320f, 0.985277652740478520f, |
| 0.989176511764526370f, 0.992479562759399410f, 0.995184719562530520f, |
| 0.997290432453155520f, 0.998795449733734130f, |
| 0.999698817729949950f, 1.000000000000000000f, 0.999698817729949950f |
| }; |
| |
| /** |
| * @brief Fast approximation to the trigonometric cosine function for floating-point data. |
| * @param[in] x input value in radians. |
| * @return cos(x). |
| */ |
| |
| float32_t arm_cos_f32( |
| float32_t x) |
| { |
| float32_t cosVal, fract, in; |
| uint32_t index; |
| uint32_t tableSize = (uint32_t) TABLE_SIZE; |
| float32_t wa, wb, wc, wd; |
| float32_t a, b, c, d; |
| float32_t *tablePtr; |
| int32_t n; |
| |
| /* input x is in radians */ |
| /* Scale the input to [0 1] range from [0 2*PI] , divide input by 2*pi */ |
| in = x * 0.159154943092f; |
| |
| /* Calculation of floor value of input */ |
| n = (int32_t) in; |
| |
| /* Make negative values towards -infinity */ |
| if(x < 0.0f) |
| { |
| n = n - 1; |
| } |
| |
| /* Map input value to [0 1] */ |
| in = in - (float32_t) n; |
| |
| /* Calculation of index of the table */ |
| index = (uint32_t) (tableSize * in); |
| |
| /* fractional value calculation */ |
| fract = ((float32_t) tableSize * in) - (float32_t) index; |
| |
| /* Initialise table pointer */ |
| tablePtr = (float32_t *) & cosTable[index]; |
| |
| /* Read four nearest values of input value from the cos table */ |
| a = *tablePtr++; |
| b = *tablePtr++; |
| c = *tablePtr++; |
| d = *tablePtr++; |
| |
| /* Cubic interpolation process */ |
| wa = -(((0.166666667f) * fract) * (fract * fract)) + |
| (((0.5f) * (fract * fract)) - ((0.3333333333333f) * fract)); |
| wb = ((((0.5f) * fract) * (fract * fract)) - (fract * fract)) + |
| (-((0.5f) * fract) + 1.0f); |
| wc = -(((0.5f) * fract) * (fract * fract)) + |
| (((0.5f) * (fract * fract)) + fract); |
| wd = (((0.166666667f) * fract) * (fract * fract)) - |
| ((0.166666667f) * fract); |
| |
| /* Calculate cos value */ |
| cosVal = ((a * wa) + (b * wb)) + ((c * wc) + (d * wd)); |
| |
| /* Return the output value */ |
| return (cosVal); |
| |
| } |
| |
| /** |
| * @} end of cos group |
| */ |