/* $License: Copyright (C) 2011-2012 InvenSense Corporation, All Rights Reserved. See included License.txt for License information. $ */ /******************************************************************************* * * $Id:$ * ******************************************************************************/ /** * @defgroup ML_MATH_FUNC ml_math_func * @brief Motion Library - Math Functions * Common math functions the Motion Library * * @{ * @file ml_math_func.c * @brief Math Functions. */ #include "mlmath.h" #include "ml_math_func.h" #include "mlinclude.h" #include #ifdef EMPL #define TABLE_SIZE (256) /* TODO: If memory becomes a big issue, we can just store the data for a single * quadrant and transform the inputs and outputs of the lookup functions. */ const float sin_lookup[TABLE_SIZE] = { 0.000000f, 0.024541f, 0.049068f, 0.073565f, 0.098017f, 0.122411f, 0.146730f, 0.170962f, 0.195090f, 0.219101f, 0.242980f, 0.266713f, 0.290285f, 0.313682f, 0.336890f, 0.359895f, 0.382683f, 0.405241f, 0.427555f, 0.449611f, 0.471397f, 0.492898f, 0.514103f, 0.534998f, 0.555570f, 0.575808f, 0.595699f, 0.615232f, 0.634393f, 0.653173f, 0.671559f, 0.689541f, 0.707107f, 0.724247f, 0.740951f, 0.757209f, 0.773010f, 0.788346f, 0.803208f, 0.817585f, 0.831470f, 0.844854f, 0.857729f, 0.870087f, 0.881921f, 0.893224f, 0.903989f, 0.914210f, 0.923880f, 0.932993f, 0.941544f, 0.949528f, 0.956940f, 0.963776f, 0.970031f, 0.975702f, 0.980785f, 0.985278f, 0.989177f, 0.992480f, 0.995185f, 0.997290f, 0.998795f, 0.999699f, 1.000000f, 0.999699f, 0.998795f, 0.997290f, 0.995185f, 0.992480f, 0.989177f, 0.985278f, 0.980785f, 0.975702f, 0.970031f, 0.963776f, 0.956940f, 0.949528f, 0.941544f, 0.932993f, 0.923880f, 0.914210f, 0.903989f, 0.893224f, 0.881921f, 0.870087f, 0.857729f, 0.844854f, 0.831470f, 0.817585f, 0.803208f, 0.788346f, 0.773010f, 0.757209f, 0.740951f, 0.724247f, 0.707107f, 0.689541f, 0.671559f, 0.653173f, 0.634393f, 0.615232f, 0.595699f, 0.575808f, 0.555570f, 0.534998f, 0.514103f, 0.492898f, 0.471397f, 0.449611f, 0.427555f, 0.405241f, 0.382683f, 0.359895f, 0.336890f, 0.313682f, 0.290285f, 0.266713f, 0.242980f, 0.219101f, 0.195091f, 0.170962f, 0.146731f, 0.122411f, 0.098017f, 0.073565f, 0.049068f, 0.024541f, 0.000000f, -0.024541f, -0.049067f, -0.073564f, -0.098017f, -0.122411f, -0.146730f, -0.170962f, -0.195090f, -0.219101f, -0.242980f, -0.266713f, -0.290284f, -0.313682f, -0.336890f, -0.359895f, -0.382683f, -0.405241f, -0.427555f, -0.449611f, -0.471397f, -0.492898f, -0.514103f, -0.534997f, -0.555570f, -0.575808f, -0.595699f, -0.615231f, -0.634393f, -0.653173f, -0.671559f, -0.689540f, -0.707107f, -0.724247f, -0.740951f, -0.757209f, -0.773010f, -0.788346f, -0.803207f, -0.817585f, -0.831469f, -0.844853f, -0.857729f, -0.870087f, -0.881921f, -0.893224f, -0.903989f, -0.914210f, -0.923880f, -0.932993f, -0.941544f, -0.949528f, -0.956940f, -0.963776f, -0.970031f, -0.975702f, -0.980785f, -0.985278f, -0.989176f, -0.992480f, -0.995185f, -0.997290f, -0.998795f, -0.999699f, -1.000000f, -0.999699f, -0.998795f, -0.997290f, -0.995185f, -0.992480f, -0.989177f, -0.985278f, -0.980785f, -0.975702f, -0.970031f, -0.963776f, -0.956940f, -0.949528f, -0.941544f, -0.932993f, -0.923880f, -0.914210f, -0.903989f, -0.893224f, -0.881921f, -0.870087f, -0.857729f, -0.844854f, -0.831470f, -0.817585f, -0.803208f, -0.788347f, -0.773011f, -0.757209f, -0.740951f, -0.724247f, -0.707107f, -0.689541f, -0.671559f, -0.653173f, -0.634394f, -0.615232f, -0.595699f, -0.575808f, -0.555570f, -0.534998f, -0.514103f, -0.492898f, -0.471397f, -0.449612f, -0.427555f, -0.405241f, -0.382684f, -0.359895f, -0.336890f, -0.313682f, -0.290285f, -0.266713f, -0.242981f, -0.219102f, -0.195091f, -0.170962f, -0.146731f, -0.122411f, -0.098017f, -0.073565f, -0.049068f, -0.024542f }; float inv_sinf(float x) { int index = (unsigned int)((x * (TABLE_SIZE>>1)) / 3.14159f) % TABLE_SIZE; return sin_lookup[index]; } float inv_cosf(float x) { int index = ((unsigned int)((x * (TABLE_SIZE>>1)) / 3.14159f) + (TABLE_SIZE>>2)) % TABLE_SIZE; return sin_lookup[index]; } #endif /** @internal * Does the cross product of compass by gravity, then converts that * to the world frame using the quaternion, then computes the angle that * is made. * * @param[in] compass Compass Vector (Body Frame), length 3 * @param[in] grav Gravity Vector (Body Frame), length 3 * @param[in] quat Quaternion, Length 4 * @return Angle Cross Product makes after quaternion rotation. */ float inv_compass_angle(const long *compass, const long *grav, const long *quat) { long cgcross[4], q1[4], q2[4], qi[4]; float angW; // Compass cross Gravity cgcross[0] = 0L; cgcross[1] = inv_q30_mult(compass[1], grav[2]) - inv_q30_mult(compass[2], grav[1]); cgcross[2] = inv_q30_mult(compass[2], grav[0]) - inv_q30_mult(compass[0], grav[2]); cgcross[3] = inv_q30_mult(compass[0], grav[1]) - inv_q30_mult(compass[1], grav[0]); // Now convert cross product into world frame inv_q_mult(quat, cgcross, q1); inv_q_invert(quat, qi); inv_q_mult(q1, qi, q2); // Protect against atan2 of 0,0 if ((q2[2] == 0L) && (q2[1] == 0L)) return 0.f; // This is the unfiltered heading correction angW = -atan2f(inv_q30_to_float(q2[2]), inv_q30_to_float(q2[1])); return angW; } /** * @brief The gyro data magnitude squared : * (1 degree per second)^2 = 2^6 = 2^GYRO_MAG_SQR_SHIFT. * @param[in] gyro Gyro data scaled with 1 dps = 2^16 * @return the computed magnitude squared output of the gyroscope. */ unsigned long inv_get_gyro_sum_of_sqr(const long *gyro) { unsigned long gmag = 0; long temp; int kk; for (kk = 0; kk < 3; ++kk) { temp = gyro[kk] >> (16 - (GYRO_MAG_SQR_SHIFT / 2)); gmag += temp * temp; } return gmag; } /** Performs a multiply and shift by 29. These are good functions to write in assembly on * with devices with small memory where you want to get rid of the long long which some * assemblers don't handle well * @param[in] a * @param[in] b * @return ((long long)a*b)>>29 */ long inv_q29_mult(long a, long b) { #ifdef EMPL_NO_64BIT long result; result = (long)((float)a * b / (1L << 29)); return result; #else long long temp; long result; temp = (long long)a * b; result = (long)(temp >> 29); return result; #endif } /** Performs a multiply and shift by 30. These are good functions to write in assembly on * with devices with small memory where you want to get rid of the long long which some * assemblers don't handle well * @param[in] a * @param[in] b * @return ((long long)a*b)>>30 */ long inv_q30_mult(long a, long b) { #ifdef EMPL_NO_64BIT long result; result = (long)((float)a * b / (1L << 30)); return result; #else long long temp; long result; temp = (long long)a * b; result = (long)(temp >> 30); return result; #endif } #ifndef EMPL_NO_64BIT long inv_q30_div(long a, long b) { long long temp; long result; temp = (((long long)a) << 30) / b; result = (long)temp; return result; } #endif /** Performs a multiply and shift by shift. These are good functions to write * in assembly on with devices with small memory where you want to get rid of * the long long which some assemblers don't handle well * @param[in] a First multicand * @param[in] b Second multicand * @param[in] shift Shift amount after multiplying * @return ((long long)a*b)<> shift); return result; } #endif /** Performs a fixed point quaternion multiply. * @param[in] q1 First Quaternion Multicand, length 4. 1.0 scaled * to 2^30 * @param[in] q2 Second Quaternion Multicand, length 4. 1.0 scaled * to 2^30 * @param[out] qProd Product after quaternion multiply. Length 4. * 1.0 scaled to 2^30. */ void inv_q_mult(const long *q1, const long *q2, long *qProd) { INVENSENSE_FUNC_START; qProd[0] = inv_q30_mult(q1[0], q2[0]) - inv_q30_mult(q1[1], q2[1]) - inv_q30_mult(q1[2], q2[2]) - inv_q30_mult(q1[3], q2[3]); qProd[1] = inv_q30_mult(q1[0], q2[1]) + inv_q30_mult(q1[1], q2[0]) + inv_q30_mult(q1[2], q2[3]) - inv_q30_mult(q1[3], q2[2]); qProd[2] = inv_q30_mult(q1[0], q2[2]) - inv_q30_mult(q1[1], q2[3]) + inv_q30_mult(q1[2], q2[0]) + inv_q30_mult(q1[3], q2[1]); qProd[3] = inv_q30_mult(q1[0], q2[3]) + inv_q30_mult(q1[1], q2[2]) - inv_q30_mult(q1[2], q2[1]) + inv_q30_mult(q1[3], q2[0]); } /** Performs a fixed point quaternion addition. * @param[in] q1 First Quaternion term, length 4. 1.0 scaled * to 2^30 * @param[in] q2 Second Quaternion term, length 4. 1.0 scaled * to 2^30 * @param[out] qSum Sum after quaternion summation. Length 4. * 1.0 scaled to 2^30. */ void inv_q_add(long *q1, long *q2, long *qSum) { INVENSENSE_FUNC_START; qSum[0] = q1[0] + q2[0]; qSum[1] = q1[1] + q2[1]; qSum[2] = q1[2] + q2[2]; qSum[3] = q1[3] + q2[3]; } void inv_vector_normalize(long *vec, int length) { INVENSENSE_FUNC_START; double normSF = 0; int ii; for (ii = 0; ii < length; ii++) { normSF += inv_q30_to_double(vec[ii]) * inv_q30_to_double(vec[ii]); } if (normSF > 0) { normSF = 1 / sqrt(normSF); for (ii = 0; ii < length; ii++) { vec[ii] = (int)((double)vec[ii] * normSF); } } else { vec[0] = 1073741824L; for (ii = 1; ii < length; ii++) { vec[ii] = 0; } } } void inv_q_normalize(long *q) { INVENSENSE_FUNC_START; inv_vector_normalize(q, 4); } void inv_q_invert(const long *q, long *qInverted) { INVENSENSE_FUNC_START; qInverted[0] = q[0]; qInverted[1] = -q[1]; qInverted[2] = -q[2]; qInverted[3] = -q[3]; } double quaternion_to_rotation_angle(const long *quat) { double quat0 = (double )quat[0] / 1073741824; if (quat0 > 1.0f) { quat0 = 1.0; } else if (quat0 < -1.0f) { quat0 = -1.0; } return acos(quat0)*2*180/M_PI; } /** Rotates a 3-element vector by Rotation defined by Q */ void inv_q_rotate(const long *q, const long *in, long *out) { long q_temp1[4], q_temp2[4]; long in4[4], out4[4]; // Fixme optimize in4[0] = 0; memcpy(&in4[1], in, 3 * sizeof(long)); inv_q_mult(q, in4, q_temp1); inv_q_invert(q, q_temp2); inv_q_mult(q_temp1, q_temp2, out4); memcpy(out, &out4[1], 3 * sizeof(long)); } void inv_q_multf(const float *q1, const float *q2, float *qProd) { INVENSENSE_FUNC_START; qProd[0] = (q1[0] * q2[0] - q1[1] * q2[1] - q1[2] * q2[2] - q1[3] * q2[3]); qProd[1] = (q1[0] * q2[1] + q1[1] * q2[0] + q1[2] * q2[3] - q1[3] * q2[2]); qProd[2] = (q1[0] * q2[2] - q1[1] * q2[3] + q1[2] * q2[0] + q1[3] * q2[1]); qProd[3] = (q1[0] * q2[3] + q1[1] * q2[2] - q1[2] * q2[1] + q1[3] * q2[0]); } void inv_q_addf(const float *q1, const float *q2, float *qSum) { INVENSENSE_FUNC_START; qSum[0] = q1[0] + q2[0]; qSum[1] = q1[1] + q2[1]; qSum[2] = q1[2] + q2[2]; qSum[3] = q1[3] + q2[3]; } void inv_q_normalizef(float *q) { INVENSENSE_FUNC_START; float normSF = 0; float xHalf = 0; normSF = (q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]); if (normSF < 2) { xHalf = 0.5f * normSF; normSF = normSF * (1.5f - xHalf * normSF * normSF); normSF = normSF * (1.5f - xHalf * normSF * normSF); normSF = normSF * (1.5f - xHalf * normSF * normSF); normSF = normSF * (1.5f - xHalf * normSF * normSF); q[0] *= normSF; q[1] *= normSF; q[2] *= normSF; q[3] *= normSF; } else { q[0] = 1.0; q[1] = 0.0; q[2] = 0.0; q[3] = 0.0; } normSF = (q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]); } /** Performs a length 4 vector normalization with a square root. * @param[in,out] q vector to normalize. Returns [1,0,0,0] is magnitude is zero. */ void inv_q_norm4(float *q) { float mag; mag = sqrtf(q[0] * q[0] + q[1] * q[1] + q[2] * q[2] + q[3] * q[3]); if (mag) { q[0] /= mag; q[1] /= mag; q[2] /= mag; q[3] /= mag; } else { q[0] = 1.f; q[1] = 0.f; q[2] = 0.f; q[3] = 0.f; } } void inv_q_invertf(const float *q, float *qInverted) { INVENSENSE_FUNC_START; qInverted[0] = q[0]; qInverted[1] = -q[1]; qInverted[2] = -q[2]; qInverted[3] = -q[3]; } /** * Converts a quaternion to a rotation matrix. * @param[in] quat 4-element quaternion in fixed point. One is 2^30. * @param[out] rot Rotation matrix in fixed point. One is 2^30. The * First 3 elements of the rotation matrix, represent * the first row of the matrix. Rotation matrix multiplied * by a 3 element column vector transform a vector from Body * to World. */ void inv_quaternion_to_rotation(const long *quat, long *rot) { rot[0] = inv_q29_mult(quat[1], quat[1]) + inv_q29_mult(quat[0], quat[0]) - 1073741824L; rot[1] = inv_q29_mult(quat[1], quat[2]) - inv_q29_mult(quat[3], quat[0]); rot[2] = inv_q29_mult(quat[1], quat[3]) + inv_q29_mult(quat[2], quat[0]); rot[3] = inv_q29_mult(quat[1], quat[2]) + inv_q29_mult(quat[3], quat[0]); rot[4] = inv_q29_mult(quat[2], quat[2]) + inv_q29_mult(quat[0], quat[0]) - 1073741824L; rot[5] = inv_q29_mult(quat[2], quat[3]) - inv_q29_mult(quat[1], quat[0]); rot[6] = inv_q29_mult(quat[1], quat[3]) - inv_q29_mult(quat[2], quat[0]); rot[7] = inv_q29_mult(quat[2], quat[3]) + inv_q29_mult(quat[1], quat[0]); rot[8] = inv_q29_mult(quat[3], quat[3]) + inv_q29_mult(quat[0], quat[0]) - 1073741824L; } /** * Converts a quaternion to a rotation vector. A rotation vector is * a method to represent a 4-element quaternion vector in 3-elements. * To get the quaternion from the 3-elements, The last 3-elements of * the quaternion will be the given rotation vector. The first element * of the quaternion will be the positive value that will be required * to make the magnitude of the quaternion 1.0 or 2^30 in fixed point units. * @param[in] quat 4-element quaternion in fixed point. One is 2^30. * @param[out] rot Rotation vector in fixed point. One is 2^30. */ void inv_quaternion_to_rotation_vector(const long *quat, long *rot) { rot[0] = quat[1]; rot[1] = quat[2]; rot[2] = quat[3]; if (quat[0] < 0.0) { rot[0] = -rot[0]; rot[1] = -rot[1]; rot[2] = -rot[2]; } } /** Converts a 32-bit long to a big endian byte stream */ unsigned char *inv_int32_to_big8(long x, unsigned char *big8) { big8[0] = (unsigned char)((x >> 24) & 0xff); big8[1] = (unsigned char)((x >> 16) & 0xff); big8[2] = (unsigned char)((x >> 8) & 0xff); big8[3] = (unsigned char)(x & 0xff); return big8; } /** Converts a big endian byte stream into a 32-bit long */ long inv_big8_to_int32(const unsigned char *big8) { long x; x = ((long)big8[0] << 24) | ((long)big8[1] << 16) | ((long)big8[2] << 8) | ((long)big8[3]); return x; } /** Converts a big endian byte stream into a 16-bit integer (short) */ short inv_big8_to_int16(const unsigned char *big8) { short x; x = ((short)big8[0] << 8) | ((short)big8[1]); return x; } /** Converts a little endian byte stream into a 16-bit integer (short) */ short inv_little8_to_int16(const unsigned char *little8) { short x; x = ((short)little8[1] << 8) | ((short)little8[0]); return x; } /** Converts a 16-bit short to a big endian byte stream */ unsigned char *inv_int16_to_big8(short x, unsigned char *big8) { big8[0] = (unsigned char)((x >> 8) & 0xff); big8[1] = (unsigned char)(x & 0xff); return big8; } void inv_matrix_det_inc(float *a, float *b, int *n, int x, int y) { int k, l, i, j; for (i = 0, k = 0; i < *n; i++, k++) { for (j = 0, l = 0; j < *n; j++, l++) { if (i == x) i++; if (j == y) j++; *(b + 6 * k + l) = *(a + 6 * i + j); } } *n = *n - 1; } void inv_matrix_det_incd(double *a, double *b, int *n, int x, int y) { int k, l, i, j; for (i = 0, k = 0; i < *n; i++, k++) { for (j = 0, l = 0; j < *n; j++, l++) { if (i == x) i++; if (j == y) j++; *(b + 6 * k + l) = *(a + 6 * i + j); } } *n = *n - 1; } float inv_matrix_det(float *p, int *n) { float d[6][6], sum = 0; int i, j, m; m = *n; if (*n == 2) return (*p ** (p + 7) - *(p + 1) ** (p + 6)); for (i = 0, j = 0; j < m; j++) { *n = m; inv_matrix_det_inc(p, &d[0][0], n, i, j); sum = sum + *(p + 6 * i + j) * SIGNM(i + j) * inv_matrix_det(&d[0][0], n); } return (sum); } double inv_matrix_detd(double *p, int *n) { double d[6][6], sum = 0; int i, j, m; m = *n; if (*n == 2) return (*p ** (p + 7) - *(p + 1) ** (p + 6)); for (i = 0, j = 0; j < m; j++) { *n = m; inv_matrix_det_incd(p, &d[0][0], n, i, j); sum = sum + *(p + 6 * i + j) * SIGNM(i + j) * inv_matrix_detd(&d[0][0], n); } return (sum); } /** Wraps angle from (-M_PI,M_PI] * @param[in] ang Angle in radians to wrap * @return Wrapped angle from (-M_PI,M_PI] */ float inv_wrap_angle(float ang) { if (ang > M_PI) return ang - 2 * (float)M_PI; else if (ang <= -(float)M_PI) return ang + 2 * (float)M_PI; else return ang; } /** Finds the minimum angle difference ang1-ang2 such that difference * is between [-M_PI,M_PI] * @param[in] ang1 * @param[in] ang2 * @return angle difference ang1-ang2 */ float inv_angle_diff(float ang1, float ang2) { float d; ang1 = inv_wrap_angle(ang1); ang2 = inv_wrap_angle(ang2); d = ang1 - ang2; if (d > M_PI) d -= 2 * (float)M_PI; else if (d < -(float)M_PI) d += 2 * (float)M_PI; return d; } /** bernstein hash, derived from public domain source */ uint32_t inv_checksum(const unsigned char *str, int len) { uint32_t hash = 5381; int i, c; for (i = 0; i < len; i++) { c = *(str + i); hash = ((hash << 5) + hash) + c; /* hash * 33 + c */ } return hash; } static unsigned short inv_row_2_scale(const signed char *row) { unsigned short b; if (row[0] > 0) b = 0; else if (row[0] < 0) b = 4; else if (row[1] > 0) b = 1; else if (row[1] < 0) b = 5; else if (row[2] > 0) b = 2; else if (row[2] < 0) b = 6; else b = 7; // error return b; } /** Converts an orientation matrix made up of 0,+1,and -1 to a scalar representation. * @param[in] mtx Orientation matrix to convert to a scalar. * @return Description of orientation matrix. The lowest 2 bits (0 and 1) represent the column the one is on for the * first row, with the bit number 2 being the sign. The next 2 bits (3 and 4) represent * the column the one is on for the second row with bit number 5 being the sign. * The next 2 bits (6 and 7) represent the column the one is on for the third row with * bit number 8 being the sign. In binary the identity matrix would therefor be: * 010_001_000 or 0x88 in hex. */ unsigned short inv_orientation_matrix_to_scalar(const signed char *mtx) { unsigned short scalar; /* XYZ 010_001_000 Identity Matrix XZY 001_010_000 YXZ 010_000_001 YZX 000_010_001 ZXY 001_000_010 ZYX 000_001_010 */ scalar = inv_row_2_scale(mtx); scalar |= inv_row_2_scale(mtx + 3) << 3; scalar |= inv_row_2_scale(mtx + 6) << 6; return scalar; } /** Uses the scalar orientation value to convert from chip frame to body frame * @param[in] orientation A scalar that represent how to go from chip to body frame * @param[in] input Input vector, length 3 * @param[out] output Output vector, length 3 */ void inv_convert_to_body(unsigned short orientation, const long *input, long *output) { output[0] = input[orientation & 0x03] * SIGNSET(orientation & 0x004); output[1] = input[(orientation>>3) & 0x03] * SIGNSET(orientation & 0x020); output[2] = input[(orientation>>6) & 0x03] * SIGNSET(orientation & 0x100); } /** Uses the scalar orientation value to convert from body frame to chip frame * @param[in] orientation A scalar that represent how to go from chip to body frame * @param[in] input Input vector, length 3 * @param[out] output Output vector, length 3 */ void inv_convert_to_chip(unsigned short orientation, const long *input, long *output) { output[orientation & 0x03] = input[0] * SIGNSET(orientation & 0x004); output[(orientation>>3) & 0x03] = input[1] * SIGNSET(orientation & 0x020); output[(orientation>>6) & 0x03] = input[2] * SIGNSET(orientation & 0x100); } /** Uses the scalar orientation value to convert from chip frame to body frame and * apply appropriate scaling. * @param[in] orientation A scalar that represent how to go from chip to body frame * @param[in] sensitivity Sensitivity scale * @param[in] input Input vector, length 3 * @param[out] output Output vector, length 3 */ void inv_convert_to_body_with_scale(unsigned short orientation, long sensitivity, const long *input, long *output) { output[0] = inv_q30_mult(input[orientation & 0x03] * SIGNSET(orientation & 0x004), sensitivity); output[1] = inv_q30_mult(input[(orientation>>3) & 0x03] * SIGNSET(orientation & 0x020), sensitivity); output[2] = inv_q30_mult(input[(orientation>>6) & 0x03] * SIGNSET(orientation & 0x100), sensitivity); } /** find a norm for a vector * @param[in] a vector [3x1] * @param[out] output the norm of the input vector */ double inv_vector_norm(const float *x) { return sqrt(x[0]*x[0]+x[1]*x[1]+x[2]*x[2]); } void inv_init_biquad_filter(inv_biquad_filter_t *pFilter, float *pBiquadCoeff) { int i; // initial state to zero pFilter->state[0] = 0; pFilter->state[1] = 0; // set up coefficients for (i=0; i<5; i++) { pFilter->c[i] = pBiquadCoeff[i]; } } void inv_calc_state_to_match_output(inv_biquad_filter_t *pFilter, float input) { pFilter->input = input; pFilter->output = input; pFilter->state[0] = input / (1 + pFilter->c[2] + pFilter->c[3]); pFilter->state[1] = pFilter->state[0]; } float inv_biquad_filter_process(inv_biquad_filter_t *pFilter, float input) { float stateZero; pFilter->input = input; // calculate the new state; stateZero = pFilter->input - pFilter->c[2]*pFilter->state[0] - pFilter->c[3]*pFilter->state[1]; pFilter->output = stateZero + pFilter->c[0]*pFilter->state[0] + pFilter->c[1]*pFilter->state[1]; // update the output and state pFilter->output = pFilter->output * pFilter->c[4]; pFilter->state[1] = pFilter->state[0]; pFilter->state[0] = stateZero; return pFilter->output; } void inv_get_cross_product_vec(float *cgcross, float compass[3], float grav[3]) { cgcross[0] = (float)compass[1] * grav[2] - (float)compass[2] * grav[1]; cgcross[1] = (float)compass[2] * grav[0] - (float)compass[0] * grav[2]; cgcross[2] = (float)compass[0] * grav[1] - (float)compass[1] * grav[0]; } void mlMatrixVectorMult(long matrix[9], const long vecIn[3], long *vecOut) { // matrix format // [ 0 3 6; // 1 4 7; // 2 5 8] // vector format: [0 1 2]^T; int i, j; long temp; for (i=0; i<3; i++) { temp = 0; for (j=0; j<3; j++) { temp += inv_q30_mult(matrix[i+j*3], vecIn[j]); } vecOut[i] = temp; } } /** * @} */