1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef bbs_PHASE_EM_H 18 #define bbs_PHASE_EM_H 19 20 /* ---- includes ----------------------------------------------------------- */ 21 22 /** 23 * Phase data type. 24 * This data type represents a phase or angle value and takes advantage 25 * of the circular value range when doing arithmetig with an integer 26 * by ignoring overflow. 27 * The phase value range lies within [ - PI, PI [; 28 * The corresponding integer value range is [ MININT, MAXINT + 1 [. 29 * The phase data type is to be used whereever an angle is needed. 30 */ 31 32 #include "b_BasicEm/Basic.h" 33 34 /* ---- related objects --------------------------------------------------- */ 35 36 /* ---- typedefs ----------------------------------------------------------- */ 37 38 /** 8 bit phase value */ 39 typedef int8 phase8; 40 41 /** 16 bit phase value */ 42 typedef int16 phase16; 43 44 /** 32 bit phase value */ 45 typedef int32 phase32; 46 47 /* ---- constants ---------------------------------------------------------- */ 48 49 /** value PI in a phase16 expression */ 50 #define bbs_M_PI_16 32768 51 52 /** value PI/2 in a phase16 expression */ 53 #define bbs_M_PI_2_16 16384 54 55 /** value PI/4 in a phase16 expression */ 56 #define bbs_M_PI_4_16 8192 57 58 /** value PI in a phase8 expression */ 59 #define bbs_M_PI_8 128 60 61 /** value PI/2 in a phase8 expression */ 62 #define bbs_M_PI_2_8 64 63 64 /** value ( 32768 / PI ) in the format 14.1 */ 65 #define bbs_PHASE_MAX_BY_PI 20861 66 67 /** sine interpolation method */ 68 #define bbs_SIN_INTERPOLATION_METHOD_2 69 70 /* ---- object definition -------------------------------------------------- */ 71 72 /* ---- associated objects ------------------------------------------------- */ 73 74 /* ---- external functions ------------------------------------------------- */ 75 76 /* ---- \ghd{ constructor/destructor } ------------------------------------- */ 77 78 /* ---- \ghd{ operators } -------------------------------------------------- */ 79 80 /* ---- \ghd{ query functions } -------------------------------------------- */ 81 82 /** 83 * Computes sine of a phase 84 * The return value has the format 8.24 85 * The function approximates ( int32 )( sin( ( M_PI * phaseA ) / ( 1<<15 ) ) * ( 1<<24 ) ) 86 * Max error: 8.5E-5 (METHOD1); 7.0E-5 (METHOD2) 87 * Std error: 4.4E-5 (METHOD1); 3.2E-5 (METHOD2) 88 */ 89 int32 bbs_sin32( phase16 phaseA ); 90 91 /** 92 * Computes cosine of a phase 93 * The return value has the format 8.24 94 * The function approximates ( int32 )( cos( ( M_PI * phaseA ) / ( 1<<15 ) ) * ( 1<<24 ) ) 95 * Max error: 8.5E-5 (METHOD1); 7.0E-5 (METHOD2) 96 * Std error: 4.4E-5 (METHOD1); 3.2E-5 (METHOD2) 97 */ 98 int32 bbs_cos32( phase16 phaseA ); 99 100 /** 101 * Computes sine of a phase 102 * The return value has the format 2.14 103 * see sin32 for details 104 */ 105 int16 bbs_sin16( phase16 phaseA ); 106 107 /** 108 * Computes cosine of a phase 109 * The return value has the format 2.14 110 * see cos32 for details 111 */ 112 int16 bbs_cos16( phase16 phaseA ); 113 114 /** 115 * Computes arcus tangens between [0,1[, where valA has the format 16.16 116 * The function approximates ( int16 )( atan( double( valA ) / ( ( 1 << 16 ) ) / M_PI ) * ( 1 << 15 ) ) 117 * Max error: 5.1E-5 PI 118 * Std error: 2.7E-5 PI 119 */ 120 phase16 bbs_atan16( uint32 valA ); 121 122 /** 123 * Computes phase from a 2d vector as angle enclosed between vector and (0,0). 124 * It is vec = ( cos( angle ), sin( angle ) ); 125 * Max error: 5.4E-5 PI 126 * Std error: 2.9E-5 PI 127 */ 128 phase16 bbs_phase16( int32 xA, int32 yA ); 129 130 /* ---- \ghd{ modify functions } ------------------------------------------- */ 131 132 /* ---- \ghd{ memory I/O } ------------------------------------------------- */ 133 134 /* ---- \ghd{ exec functions } --------------------------------------------- */ 135 136 #endif /* bbs_PHASE_EM_H */ 137 138
