Go to the documentation of this file.00001
00002
00003
00004
00005
00006
00007
00008
00009
00010
00011
00012
00013
00014
00015
00016
00017
00018
00019
00020
00021
00022
00023
00024
00025
00026
00027 #include "arm_math.h"
00028 #include "arm_common_tables.h"
00029
00030
00048 arm_status arm_sqrt_q15(
00049 q15_t in,
00050 q15_t * pOut)
00051 {
00052 q31_t out;
00053 q31_t prevOut;
00054 q15_t oneByOut;
00055 uint32_t sign_bits;
00056
00057 if(in > 0)
00058 {
00059
00060
00061
00062 out = ((q31_t) in >> 1u) + 0x3FFF;
00063
00064
00065
00066
00067 sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
00068
00069
00070 out = out >> 1u;
00071
00072 prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00073
00074
00075 sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
00076 prevOut = prevOut >> 1u;
00077 out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00078
00079 sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
00080 out = out >> 1u;
00081 prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00082
00083
00084 sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
00085 prevOut = prevOut >> 1u;
00086 out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00087
00088 sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
00089 out = out >> 1u;
00090 prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00091
00092
00093 sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
00094 prevOut = prevOut >> 1u;
00095 out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00096
00097 sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
00098 out = out >> 1u;
00099 prevOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00100
00101 sign_bits = arm_recip_q15((q15_t) prevOut, &oneByOut, armRecipTableQ15);
00102 prevOut = prevOut >> 1u;
00103 out = prevOut + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00104
00105
00106 sign_bits = arm_recip_q15((q15_t) out, &oneByOut, armRecipTableQ15);
00107 out = out >> 1u;
00108 *pOut = out + (((q15_t) (((q31_t) in * oneByOut) >> 16)) << sign_bits);
00109
00110 return (ARM_MATH_SUCCESS);
00111 }
00112 else
00113 {
00114
00115 *pOut = 0;
00116 return (ARM_MATH_ARGUMENT_ERROR);
00117 }
00118
00119 }
00120