1 /*- 2 * Copyright (c) 2016 Adrian Chadd <adrian@FreeBSD.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer, 10 * without modification. 11 * 2. Redistributions in binary form must reproduce at minimum a disclaimer 12 * similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any 13 * redistribution must be conditioned upon including a substantially 14 * similar Disclaimer requirement for further binary redistribution. 15 * 16 * NO WARRANTY 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 * LIMITED TO, THE IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTIBILITY 20 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 21 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, 22 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER 25 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 27 * THE POSSIBILITY OF SUCH DAMAGES. 28 */ 29 #ifndef __IF_BWN_CORDIC_H__ 30 #define __IF_BWN_CORDIC_H__ 31 32 /* 33 * These functions are used by the PHY code. 34 */ 35 36 /* Complex number using 2 32-bit signed integers */ 37 struct bwn_c32 { 38 int32_t i; 39 int32_t q; 40 }; 41 42 #define CORDIC_CONVERT(value) (((value) >= 0) ? \ 43 ((((value) >> 15) + 1) >> 1) : \ 44 -((((-(value)) >> 15) + 1) >> 1)) 45 46 static const uint32_t bwn_arctg[] = { 47 2949120, 1740967, 919879, 466945, 234379, 117304, 58666, 29335, 14668, 48 7334, 3667, 1833, 917, 458, 229, 115, 57, 29, 49 }; 50 51 /* http://bcm-v4.sipsolutions.net/802.11/PHY/Cordic */ 52 static inline struct bwn_c32 53 bwn_cordic(int theta) 54 { 55 uint8_t i; 56 int32_t tmp; 57 int8_t signx = 1; 58 uint32_t angle = 0; 59 struct bwn_c32 ret = { .i = 39797, .q = 0, }; 60 61 while (theta > (180 << 16)) 62 theta -= (360 << 16); 63 while (theta < -(180 << 16)) 64 theta += (360 << 16); 65 66 if (theta > (90 << 16)) { 67 theta -= (180 << 16); 68 signx = -1; 69 } else if (theta < -(90 << 16)) { 70 theta += (180 << 16); 71 signx = -1; 72 } 73 74 for (i = 0; i <= 17; i++) { 75 if (theta > angle) { 76 tmp = ret.i - (ret.q >> i); 77 ret.q += ret.i >> i; 78 ret.i = tmp; 79 angle += bwn_arctg[i]; 80 } else { 81 tmp = ret.i + (ret.q >> i); 82 ret.q -= ret.i >> i; 83 ret.i = tmp; 84 angle -= bwn_arctg[i]; 85 } 86 } 87 88 ret.i *= signx; 89 ret.q *= signx; 90 91 return ret; 92 } 93 94 #endif /* __IF_BWN_CORDIC_H__ */ 95