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| 1 | 6 | kaklik | /*! \file fixedpt.c \brief Fixed-point math function library. */ |
| 2 | //***************************************************************************** |
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| 3 | // |
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| 4 | // File Name : 'fixedpt.c' |
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| 5 | // Title : Fixed-point math function library |
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| 6 | // Author : Pascal Stang - Copyright (C) 2003 |
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| 7 | // Created : 2003.01.26 |
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| 8 | // Revised : 2003.02.02 |
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| 9 | // Version : 0.1 |
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| 10 | // Target MCU : Atmel AVR Series |
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| 11 | // Editor Tabs : 4 |
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| 12 | // |
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| 13 | // NOTE: This code is currently below version 1.0, and therefore is considered |
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| 14 | // to be lacking in some functionality or documentation, or may not be fully |
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| 15 | // tested. Nonetheless, you can expect most functions to work. |
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| 16 | // |
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| 17 | // This code is distributed under the GNU Public License |
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| 18 | // which can be found at http://www.gnu.org/licenses/gpl.txt |
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| 19 | // |
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| 20 | //***************************************************************************** |
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| 21 | |||
| 22 | |||
| 23 | #include "fixedpt.h" |
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| 24 | |||
| 25 | // Program ROM constants |
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| 26 | |||
| 27 | // Global variables |
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| 28 | u08 FixedPtBits; |
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| 29 | |||
| 30 | // Functions |
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| 31 | |||
| 32 | // fixedptInit() initializes fixed-point math function library |
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| 33 | void fixedptInit(u08 fixedPtBits) |
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| 34 | { |
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| 35 | // set the number of bits to use behind the point |
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| 36 | FixedPtBits = fixedPtBits; |
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| 37 | } |
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| 38 | |||
| 39 | s32 fixedptConvertFromInt(s32 int_number) |
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| 40 | { |
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| 41 | // convert integer to fixed-point number |
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| 42 | return (int_number<<FixedPtBits); |
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| 43 | } |
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| 44 | |||
| 45 | s32 fixedptConvertToInt(s32 fp_number) |
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| 46 | { |
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| 47 | // convert fixed-point number to integer |
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| 48 | // do rounding |
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| 49 | if( fp_number & 1<<(FixedPtBits-1) ) |
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| 50 | { |
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| 51 | // bit behind the point was a '1' |
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| 52 | // round up to next higher integer |
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| 53 | return (fp_number>>FixedPtBits)+1; |
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| 54 | } |
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| 55 | else |
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| 56 | { |
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| 57 | // bit behind the point was a '0' |
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| 58 | // round down (truncate) to next lower integer |
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| 59 | return (fp_number>>FixedPtBits); |
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| 60 | } |
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| 61 | } |
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| 62 | |||
| 63 | s32 fixedptAdd(s32 a, s32 b) |
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| 64 | { |
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| 65 | // add a and b (a+b) with fixed-point math |
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| 66 | return a+b; |
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| 67 | } |
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| 68 | |||
| 69 | s32 fixedptSubtract(s32 a, s32 b) |
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| 70 | { |
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| 71 | // subtract a and b (a-b) with fixed-point math |
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| 72 | return a-b; |
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| 73 | } |
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| 74 | |||
| 75 | s32 fixedptMultiply(s32 a, s32 b) |
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| 76 | { |
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| 77 | // multiply a and b (a*b) with fixed-point math |
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| 78 | return (a*b)>>FixedPtBits; |
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| 79 | } |
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| 80 | |||
| 81 | s32 fixedptDivide(s32 numer, s32 denom) |
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| 82 | { |
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| 83 | // divide numer by denom (numer/denom) with fixed-point math |
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| 84 | return (numer<<FixedPtBits)/denom; |
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| 85 | } |
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