568 lines
18 KiB
C
568 lines
18 KiB
C
/**
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* \defgroup fixedpoint Fixed-point based animated plasma patterns.
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*/
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/*@{*/
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/**
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* @file fpmath_patterns.c
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* @brief Routines for drawing patterns generated by fixed-point math functions.
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* @author Christian Kroll
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*/
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#include <assert.h>
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#include <stdint.h>
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#include <stddef.h>
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#include "../config.h"
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#include "../pixel.h"
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#include "../util.h"
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#include "fpmath_patterns.h"
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#ifdef DOXYGEN
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/**
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* Low precision means that we use Q10.5 values and 16 bit types for almost
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* every calculation (with multiplication and division as notable exceptions
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* as they and their interim results utilize 32 bit).
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*
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* Use this precision mode with care as image quality will suffer
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* noticeably. It produces leaner and faster code, though. This mode should
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* not be used with resolutions higher than 16x16 as overflows are likely to
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* occur in interim calculations.
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*
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* Normal precision (i.e. #undef LOW_PRECISION) conforms to Q7.8 with the
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* ability to store every interim result as Q23.8. Most operations like
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* square root, sine, cosine, multiplication etc. utilize 32 bit types.
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*/
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#define FP_LOW_PRECISION
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#endif /* DOXYGEN */
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#ifdef FP_LOW_PRECISION
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#undef FP_LOW_PRECISION
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#endif
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// low precision for displays where each dimension is less than or equal to 16
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#if NUM_COLS <= 16 && NUM_ROWS <= 16
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#define FP_LOW_PRECISION
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#endif
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#ifdef FP_LOW_PRECISION
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/** This is the type we expect ordinary integers to be. */
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typedef int16_t ordinary_int_t;
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/** This is the type which we use for fixed-point values. */
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typedef int16_t fixp_t;
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/** This type covers arguments of fixSin() and fixCos(). */
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typedef int16_t fixp_trig_t;
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/** This type covers interim results of fixed-point operations. */
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typedef uint32_t fixp_interim_t;
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/** This type covers interim results of the fixSqrt() function. */
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typedef uint16_t ufixp_interim_t;
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/** Number of bits the fixSqrt() function can handle. */
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#define SQRT_BITS 16
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// NOTE: If you change the following values, don't forget to adapt the sine
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// lookup table as well!
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/** Multiply a number by this factor to convert it to a fixed-point value.*/
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#define FIX 32
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/** Number of fractional bits of a value (i.e. ceil(log_2(FIX))). */
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#define FIX_FRACBITS 5
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/**
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* The number of temporal quantization steps of the sine lookup table. It
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* must be a divisor of (FIX * 2 * pi) and this divisor must be divisable by
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* 4 itself. Approximate this value as close as possible to keep rounding
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* errors at a minimum.
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*/
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#define FIX_SIN_COUNT 200
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/** The rounded down quotient of (FIX * 2 * pi) and FIX_SIN_COUNT */
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#define FIX_SIN_DIVIDER 1
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/** Type of the lookup table elements. */
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typedef uint8_t lut_t;
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/**
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* Lookup table of fractional parts which model the first quarter of a
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* sine period. The rest of that period is calculated by mirroring those
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* values. These values are intended for Q5 types.
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*/
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static lut_t const fix_sine_lut[FIX_SIN_COUNT / 4] =
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{ 0, 1, 2, 3, 4, 5, 6, 7,
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8, 9, 10, 11, 12, 13, 14, 14,
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15, 16, 17, 18, 19, 20, 20, 21,
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22, 23, 23, 24, 25, 25, 26, 26,
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27, 27, 28, 28, 29, 29, 30, 30,
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30, 31, 31, 31, 31, 32, 32, 32,
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32, 32};
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#else
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/** This is the type we expect ordinary integers to be. */
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typedef int16_t ordinary_int_t;
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/** This is the type which we use for fixed-point values. */
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typedef int16_t fixp_t;
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/** This type covers arguments of fixSin() and fixCos(). */
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typedef int32_t fixp_trig_t;
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/** This type covers interim results of fixed-point operations. */
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typedef int32_t fixp_interim_t;
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/** This type covers interim results of the fixSqrt() function. */
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typedef uint32_t ufixp_interim_t;
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/** Number of bits the fixSqrt() function can handle. */
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#define SQRT_BITS 32
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// NOTE: If you change the following values, don't forget to adapt the sine
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// lookup table as well!
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/** Multiply a number by this factor to convert it to a fixed-point value.*/
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#define FIX 256
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/** Number of fractional bits of a value (i.e. ceil(log_2(FIX))). */
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#define FIX_FRACBITS 8
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/**
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* The number of temporal quantization steps of the sine lookup table. It
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* must be a divisor of (FIX * 2 * pi) and this divisor must be divisable by
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* 4 itself. Approximate this value as close as possible to keep rounding
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* errors at a minimum.
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*/
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#define FIX_SIN_COUNT 200
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/** The rounded down quotient of (FIX * 2 * pi) and FIX_SIN_COUNT */
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#define FIX_SIN_DIVIDER 8
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/** Type of the lookup table elements. */
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typedef uint8_t lut_t;
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/**
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* Lookup table of fractional parts which model the first quarter of a
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* sine period. The rest of that period is calculated by mirroring those
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* values. These values are intended for Q8 types.
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*/
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static lut_t const fix_sine_lut[FIX_SIN_COUNT / 4] =
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{ 0, 9, 17, 24, 32, 40, 48, 56,
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64, 72, 79, 87, 94, 102, 109, 116,
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123, 130, 137, 144, 150, 157, 163, 169,
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175, 181, 186, 192, 197, 202, 207, 211,
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216, 220, 224, 228, 231, 235, 238, 240,
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243, 245, 247, 249, 251, 252, 253, 254,
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255, 255};
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#endif
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/** The ordinary pi constant. */
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#define PI 3.14159265358979323846
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/** Fixed-point version of (pi / 2). */
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#define FIX_PI_2 ((fixp_t)(PI * FIX / 2))
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/** Fixed-point version of pi. */
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#define FIX_PI ((fixp_t)(PI * FIX))
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/** Fixed-point version of (2 * pi). */
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#define FIX_2PI ((fixp_t)(2 * PI * FIX))
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/**
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* Scales an ordinary integer up to its fixed-point format.
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* @param a An ordinary integer to be scaled up.
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* @return The given value in fixed-point format.
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*/
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inline static fixp_t fixScaleUp(ordinary_int_t a)
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{
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return (fixp_t)a * FIX;
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}
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/**
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* Scales a fixed-point value down to an ordinary integer (omitting the
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* fractional part).
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* @param a Fixed-point value to be scaled down to an integer.
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* @return The given value as an integer.
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*/
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inline static ordinary_int_t fixScaleDown(fixp_t const a)
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{
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return a / FIX;
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}
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/**
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* Multiplies two fixed-point values.
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* @param a A multiplicand.
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* @param b A multiplying factor.
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* @return Product of a and b.
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*/
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inline static fixp_interim_t fixMul(fixp_t const a, fixp_t const b)
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{
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return ((fixp_interim_t)a * (fixp_interim_t)b) / FIX;
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}
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/**
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* Divides two fixed-point values.
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* @param a A dividend.
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* @param b A divisor.
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* @return Quotient of a and b.
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*/
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inline static fixp_t fixDiv(fixp_interim_t const a, fixp_interim_t const b)
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{
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return (a * FIX) / b;
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}
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/**
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* Fixed-point variant of the sine function which receives a fixed-point angle
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* (radian). It uses a lookup table which models the first quarter of a full
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* sine period and calculates the rest from that quarter.
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* @param fAngle A fixed-point value in radian.
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* @return Result of the sine function normalized to a range from -FIX to FIX.
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*/
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static fixp_t fixSin(fixp_trig_t fAngle)
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{
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// convert given fixed-point angle to its corresponding quantization step
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int8_t nSign = 1;
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if (fAngle < 0)
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{
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// take advantage of sin(-x) == -sin(x) to avoid neg. operands for "%"
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fAngle = -fAngle;
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nSign = -1;
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}
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uint8_t nIndex = (fAngle / FIX_SIN_DIVIDER) % FIX_SIN_COUNT;
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// now convert that quantization step to an index of our quartered array
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if ((nIndex >= (FIX_SIN_COUNT / 4)))
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{
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if (nIndex < (FIX_SIN_COUNT / 2))
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{
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nIndex = (FIX_SIN_COUNT / 2 - 1) - nIndex;
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}
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else
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{
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// an angle > PI means that we have to toggle the sign of the result
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nSign *= -1;
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if (nIndex < (FIX_SIN_COUNT - (FIX_SIN_COUNT / 4)))
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{
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nIndex = nIndex - (FIX_SIN_COUNT / 2);
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}
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else
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{
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nIndex = (FIX_SIN_COUNT - 1) - nIndex;
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}
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}
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}
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assert(nIndex < (FIX_SIN_COUNT / 4));
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return ((fixp_t)fix_sine_lut[nIndex]) * nSign;
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}
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/**
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* Fixed-point variant of the cosine function which takes a fixed-point angle
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* (radian). It adds FIX_PI_2 to the given angle and consults the fixSin()
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* function for the final result.
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* @param fAngle A fixed-point value in radian.
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* @return Result of the cosine function normalized to a range from -FIX to FIX.
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*/
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static fixp_t fixCos(fixp_trig_t const fAngle)
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{
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return fixSin(fAngle + FIX_PI_2);
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}
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/**
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* Fixed-point square root algorithm as proposed by Ken Turkowski:
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* http://www.realitypixels.com/turk/computergraphics/FixedSqrt.pdf
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* @param a The radicant we want the square root of.
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* @return The square root of the given value.
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*/
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static fixp_t fixSqrt(ufixp_interim_t const a)
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{
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ufixp_interim_t nRoot, nRemainingHigh, nRemainingLow, nTestDiv, nCount;
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nRoot = 0; // clear root
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nRemainingHigh = 0; // clear high part of partial remainder
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nRemainingLow = a; // get argument into low part of partial remainder
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nCount = (SQRT_BITS / 2 - 1) + (FIX_FRACBITS >> 1); // load loop counter
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do
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{
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nRemainingHigh =
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(nRemainingHigh << 2) | (nRemainingLow >> (SQRT_BITS - 2));
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nRemainingLow <<= 2; // get 2 bits of the argument
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nRoot <<= 1; // get ready for the next bit in the root
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nTestDiv = (nRoot << 1) + 1; // test radical
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if (nRemainingHigh >= nTestDiv)
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{
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nRemainingHigh -= nTestDiv;
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nRoot++;
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}
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} while (nCount-- != 0);
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return (fixp_t)nRoot;
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}
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/**
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* Calculates the distance between two points.
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* @param x1 x-coordinate of the first point
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* @param y1 y-coordinate of the first point
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* @param x2 x-coordinate of the second point
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* @param y2 y-coordinate of the second point
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* @return The distance between the given points.
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*/
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static fixp_t fixDist(fixp_t const x1,
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fixp_t const y1,
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fixp_t const x2,
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fixp_t const y2)
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{
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return fixSqrt(fixMul((x1 - x2), (x1 - x2)) + fixMul((y1 - y2), (y1 - y2)));
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}
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/**
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* This pointer type covers functions which return a brightness value for the
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* given coordinates and a "step" value. Applied to all coordinates of the
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* borg's display this actually results in a more or less beautiful pattern.
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* @param x x-coordinate
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* @param y y-coordinate
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* @param t A step value which changes for each frame, allowing for animations.
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* @param r A pointer to persistent data required by the pattern function.
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* @return The brightness value (0 < n <= NUM_PLANES) of the given coordinate.
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*/
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typedef unsigned char (*fpmath_pattern_func_t)(unsigned char const x,
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unsigned char const y,
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fixp_t const t,
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void *const r);
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/**
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* Draws an animated two dimensional graph for a given function f(x, y, t).
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* @param t_start A start value for the function's step variable.
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* @param t_stop A stop value for the function's step variable.
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* @param t_delta Value by which the function's step variable gets incremented.
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* @param frame_delay The frame delay in milliseconds.
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* @param fpPattern Function which generates a pattern depending on x, y and t.
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* @param r A pointer to persistent data required by the fpPattern function.
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*/
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static void fixDrawPattern(fixp_t const t_start,
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fixp_t const t_stop,
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fixp_t const t_delta,
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int const frame_delay,
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fpmath_pattern_func_t fpPattern,
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void *r)
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{
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// off-screen buffer
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unsigned char pOffScreen[NUMPLANE + 1][NUM_ROWS][LINEBYTES];
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for (fixp_t t = t_start; t < t_stop; t += t_delta)
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{
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// For performance reasons the pattern is drawn to an off-screen buffer
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// without distributing bits of higher planes down to lower ones.
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ptrdiff_t nRowColOffset = 0;
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for (unsigned char y = 0; y < UNUM_ROWS; ++y)
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{
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for (unsigned char x = 0; x < (LINEBYTES * 8u); ++x)
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{
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// Since multidimensional subscript expressions are rather
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// expensive, we just resolve the first dimension (which
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// represents the plane) and add an offset that correlates to
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// the currently processed row and column.
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*(&pOffScreen[fpPattern(x, y, t, r)][0][0] + nRowColOffset) |=
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shl_table[x % 8u];
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// increment the offset after completion of a byte
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if ((x % 8u) == 7u)
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{
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nRowColOffset++;
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}
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}
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}
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// one byte behind the frame buffer
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unsigned char *pPixmap =
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(&pixmap[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1]) + 1;
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// one byte behind the off-screen buffer
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unsigned char *pOffscreenDistHigh =
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(&pOffScreen[NUMPLANE][NUM_ROWS - 1][LINEBYTES - 1]) + 1;
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// one byte behind the second last plane of the off-screen buffer
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unsigned char *pOffscreenDistLow =
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(&pOffScreen[NUMPLANE - 1][NUM_ROWS - 1][LINEBYTES - 1]) + 1;
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// Here we transcribe the off-screen contents to the actual frame buffer
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// by distributing down 8 bits in parallel per iteration. We start at
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// the end of both buffers and move backwards through their space.
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// The pre-decrement operator is used so that GCC utilizes the AVR's
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// built-in pre-decrement variants of the "ld" and "st" instructions.
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while (pPixmap != &pixmap[0][0][0]) // stop at the beginning
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{
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// actually draw off-screen contents
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*(--pPixmap) = *(--pOffscreenDistHigh);
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// distribute bits down to the next lower plane
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*(--pOffscreenDistLow) |= *pOffscreenDistHigh;
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// clear already drawn off-screen contents
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*pOffscreenDistHigh = 0;
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}
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// wait a moment to ensure that the current frame is visible
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wait(frame_delay);
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}
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}
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#ifdef ANIMATION_PLASMA
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/**
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* This type maintains values relevant for the Plasma animation which need to be
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* persistent over consecutive invocations.
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* @see fixAnimPlasma()
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*/
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typedef struct fixp_plasma_s
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{
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/**
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* This array holds column dependent results of the first internal pattern
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* function. Those results only need to be calculated for the first row of
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* the current frame and are then reused for the remaining rows.
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*/
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fixp_t fFunc1[LINEBYTES * 8u];
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/**
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* This value is part of the formula for the second internal pattern
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* function. It needs to be calculated only once per frame.
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*/
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fixp_t fFunc2CosArg;
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/**
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* This value is part of the formula for the second internal pattern
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* function. It needs to be calculated only once per frame.
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*/
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fixp_t fFunc2SinArg;
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} fixp_plasma_t;
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/**
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* Generates a plasma like pattern (sort of... four shades of grey are pretty
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* scarce for a neat plasma animation). This is realized by superimposing two
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* functions which generate independent patterns for themselves.
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*
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* The first function draws horizontally moving waves and the second function
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* draws zoomed-in radiating curls. Together they create a wobbly, plasma like
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* pattern.
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*
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* @param x x-coordinate
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* @param y y-coordinate
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* @param t A Step value which changes for each frame, allowing for animations.
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* @param r A pointer to persistent interim results.
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* @return The brightness value (0 < n <= NUM_PLANES) of the given coordinate.
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*/
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static unsigned char fixAnimPlasma(unsigned char const x,
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unsigned char const y,
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fixp_t const t,
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void *const r)
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{
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assert(x < NUM_COLS);
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assert(y < NUM_ROWS);
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// scaling factor
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static fixp_t const fPlasmaX = (2 * PI * FIX) / NUM_COLS;
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// reentrant data
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fixp_plasma_t *const p = (fixp_plasma_t *)r;
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if (x == 0 && y == 0)
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{
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p->fFunc2CosArg = NUM_ROWS * fixCos(t) + fixScaleUp(NUM_ROWS);
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p->fFunc2SinArg = NUM_COLS * fixSin(t) + fixScaleUp(NUM_COLS);
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for (unsigned char i = LINEBYTES * 8u; i--;)
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{
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p->fFunc1[i] = fixSin(fixMul(fixScaleUp(i), fPlasmaX) + t);
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}
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}
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fixp_t const fFunc2 = fixSin(fixMul(fixDist(fixScaleUp(x), fixScaleUp(y),
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p->fFunc2SinArg, p->fFunc2CosArg), fPlasmaX));
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unsigned char const nRes = (unsigned char)(fixMul(p->fFunc1[x] + fFunc2 +
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fixScaleUp(2), ((NUMPLANE + 1) / 4.0 - 0.05) * FIX)) / FIX;
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assert (nRes <= NUMPLANE);
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return nRes;
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}
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/**
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* Starting point for the Plasma animation.
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*/
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void plasma(void)
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{
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fixp_plasma_t r;
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#ifndef __AVR__
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fixDrawPattern(0, fixScaleUp(75), 0.1 * FIX, 15, fixAnimPlasma, &r);
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#else
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#ifndef FP_PLASMA_DELAY
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#define FP_PLASMA_DELAY 1
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#endif
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fixDrawPattern(0, fixScaleUp(60), 0.1 * FIX,
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FP_PLASMA_DELAY, fixAnimPlasma, &r);
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#endif /* __AVR__ */
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}
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|
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#endif /* ANIMATION_PLASMA */
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|
|
|
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#ifdef ANIMATION_PSYCHEDELIC
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|
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/**
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* This type maintains values relevant for the Psychedelic animation which need
|
|
* to be persistent over consecutive invocations.
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|
*/
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|
typedef struct fixp_psychedelic_s
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|
{
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|
fixp_t fCos; /**< One of the column factors of the curl. */
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fixp_t fSin; /**< One of the row factors of the curl. */
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|
fixp_interim_t ft10; /**< A value involved in rotating the curl's center. */
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} fixp_psychedelic_t;
|
|
|
|
|
|
/**
|
|
* Generates flowing circular waves with a rotating center.
|
|
* @param x x-coordinate
|
|
* @param y y-coordinate
|
|
* @param t A step value which changes for each frame, allowing for animations.
|
|
* @param r A pointer to persistent interim results.
|
|
* @return The brightness value (0 < n <= NUM_PLANES) of the given coordinate.
|
|
*/
|
|
static unsigned char fixAnimPsychedelic(unsigned char const x,
|
|
unsigned char const y,
|
|
fixp_t const t,
|
|
void *const r)
|
|
{
|
|
assert(x < NUM_COLS);
|
|
assert(y < NUM_ROWS);
|
|
fixp_psychedelic_t *p = (fixp_psychedelic_t *)r;
|
|
|
|
if (x == 0 && y == 0)
|
|
{
|
|
p->fCos = NUM_COLS/2 * fixCos(t);
|
|
p->fSin = NUM_ROWS/2 * fixSin(t);
|
|
p->ft10 = fixMul(t, fixScaleUp(10));
|
|
}
|
|
|
|
unsigned char const nResult =
|
|
(unsigned char)(fixMul(fixSin(fixDist(fixScaleUp(x), fixScaleUp(y),
|
|
p->fCos, p->fSin) - p->ft10) + fixScaleUp(1),
|
|
(fixp_t)((NUMPLANE - 1.05) * FIX))) / FIX;
|
|
assert(nResult <= NUMPLANE);
|
|
|
|
return nResult;
|
|
}
|
|
|
|
|
|
/**
|
|
* Starting point for the Psychedelic animation.
|
|
*/
|
|
void psychedelic(void)
|
|
{
|
|
fixp_psychedelic_t r;
|
|
#ifndef __AVR__
|
|
fixDrawPattern(0, fixScaleUp(75), 0.1 * FIX, 30, fixAnimPsychedelic, &r);
|
|
#else
|
|
#ifndef FP_PSYCHO_DELAY
|
|
#define FP_PSYCHO_DELAY 15
|
|
#endif
|
|
fixDrawPattern(0, fixScaleUp(60), 0.1 * FIX, FP_PSYCHO_DELAY,
|
|
fixAnimPsychedelic, &r);
|
|
#endif /* __AVR__ */
|
|
}
|
|
|
|
#endif /* ANIMATION_PSYCHEDELIC */
|
|
|
|
/*@}*/
|