1 | /* |
---|---|

2 | * Copyright (c) 2011 Broadcom Corporation |

3 | * |

4 | * Permission to use, copy, modify, and/or distribute this software for any |

5 | * purpose with or without fee is hereby granted, provided that the above |

6 | * copyright notice and this permission notice appear in all copies. |

7 | * |

8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |

9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |

10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY |

11 | * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |

12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |

13 | * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |

14 | * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |

15 | */ |

16 | #include <linux/module.h> |

17 | #include <linux/cordic.h> |

18 | |

19 | static const s32 arctan_table[] = { |

20 | 2949120, |

21 | 1740967, |

22 | 919879, |

23 | 466945, |

24 | 234379, |

25 | 117304, |

26 | 58666, |

27 | 29335, |

28 | 14668, |

29 | 7334, |

30 | 3667, |

31 | 1833, |

32 | 917, |

33 | 458, |

34 | 229, |

35 | 115, |

36 | 57, |

37 | 29 |

38 | }; |

39 | |

40 | /* |

41 | * cordic_calc_iq() - calculates the i/q coordinate for given angle |

42 | * |

43 | * theta: angle in degrees for which i/q coordinate is to be calculated |

44 | * coord: function output parameter holding the i/q coordinate |

45 | */ |

46 | struct cordic_iq cordic_calc_iq(s32 theta) |

47 | { |

48 | struct cordic_iq coord; |

49 | s32 angle, valtmp; |

50 | unsigned iter; |

51 | int signx = 1; |

52 | int signtheta; |

53 | |

54 | coord.i = CORDIC_ANGLE_GEN; |

55 | coord.q = 0; |

56 | angle = 0; |

57 | |

58 | theta = CORDIC_FIXED(theta); |

59 | signtheta = (theta < 0) ? -1 : 1; |

60 | theta = ((theta + CORDIC_FIXED(180) * signtheta) % CORDIC_FIXED(360)) - |

61 | CORDIC_FIXED(180) * signtheta; |

62 | |

63 | if (CORDIC_FLOAT(theta) > 90) { |

64 | theta -= CORDIC_FIXED(180); |

65 | signx = -1; |

66 | } else if (CORDIC_FLOAT(theta) < -90) { |

67 | theta += CORDIC_FIXED(180); |

68 | signx = -1; |

69 | } |

70 | |

71 | for (iter = 0; iter < CORDIC_NUM_ITER; iter++) { |

72 | if (theta > angle) { |

73 | valtmp = coord.i - (coord.q >> iter); |

74 | coord.q += (coord.i >> iter); |

75 | angle += arctan_table[iter]; |

76 | } else { |

77 | valtmp = coord.i + (coord.q >> iter); |

78 | coord.q -= (coord.i >> iter); |

79 | angle -= arctan_table[iter]; |

80 | } |

81 | coord.i = valtmp; |

82 | } |

83 | |

84 | coord.i *= signx; |

85 | coord.q *= signx; |

86 | return coord; |

87 | } |

88 | EXPORT_SYMBOL(cordic_calc_iq); |

89 | |

90 | MODULE_DESCRIPTION("CORDIC algorithm"); |

91 | MODULE_AUTHOR("Broadcom Corporation"); |

92 | MODULE_LICENSE("Dual BSD/GPL"); |

93 |