fpmath_patterns.c: fixed some bugs which made the higher precision mode
unusable; animations look slightly different, now
This commit is contained in:
Christian Kroll
parent
3a5052900d
commit
1dff4f3885
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@ -20,18 +20,20 @@
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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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* Low precision means that we use Q9.6 values and 16 bit types for almost
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* every calculation (with multiplication being a notable exception as its
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* interim results utilize 32 bit types).
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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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* Use this precision mode with care as image quality will suffer noticeably
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* at higher resolutions. This mode should not be used with resolutions
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* higher than 16x16 as overflows are likely to occur in interim
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* calculations. It produces leaner and faster code, though.
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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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* Normal precision (i.e. #undef LOW_PRECISION) conforms to Q23.8 for actual
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* values and interim results. Operations like square root, sine, cosine,
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* multiplication etc. utilize 32 bit types. It's extremly slow on AVR, but
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* it's your only chance to run those animations on devices with resolutions
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* higher than 16x16.
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*/
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#define FP_LOW_PRECISION
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#endif /* DOXYGEN */
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@ -66,18 +68,18 @@
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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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#define FIX 64
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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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#define FIX_FRACBITS 6
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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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#define FIX_SIN_COUNT 200u
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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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#define FIX_SIN_DIVIDER 2u
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/** Type of the lookup table elements. */
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typedef uint8_t lut_t;
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@ -85,26 +87,26 @@
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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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* values. These values are intended for Q6 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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{ 0, 2, 4, 6, 8, 10, 12, 14,
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16, 18, 20, 22, 24, 25, 27, 29,
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31, 33, 34, 36, 38, 39, 41, 42,
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44, 45, 47, 48, 49, 51, 52, 53,
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54, 55, 56, 57, 58, 59, 60, 60,
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61, 61, 62, 62, 63, 63, 63, 64,
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64, 64};
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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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typedef int32_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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typedef uint32_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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@ -123,12 +125,12 @@
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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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#define FIX_SIN_COUNT 200u
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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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#define FIX_SIN_DIVIDER 8u
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/** Type of the lookup table elements. */
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typedef uint8_t lut_t;
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typedef int16_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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@ -142,7 +144,7 @@
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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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255, 256};
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#endif
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@ -252,14 +254,14 @@ static fixp_t fixSin(fixp_trig_t fAngle)
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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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* (radian). It substracts FIX_PI_2 from the given angle and consults the
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* fixSin() 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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static inline 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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return fixSin(fAngle - FIX_PI_2);
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}
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@ -275,11 +277,11 @@ static fixp_t fixSqrt(ufixp_interim_t const a)
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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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nCount = ((SQRT_BITS - 1) + FIX_FRACBITS) / 2; // 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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(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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@ -451,16 +453,16 @@ static unsigned char fixAnimPlasma(unsigned char const x,
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assert(x < (LINEBYTES * 8));
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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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// scaling factor
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static fixp_t const fPlasmaX = FIX / 3.7;
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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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p->fFunc2CosArg = NUM_COLS * (fixCos(t) + FIX);
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p->fFunc2SinArg = NUM_ROWS * (fixSin(t) + FIX);
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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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@ -470,8 +472,8 @@ static unsigned char fixAnimPlasma(unsigned char const x,
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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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unsigned char const nRes = (fixMul(p->fFunc1[x] + fFunc2 +
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2 * FIX, ((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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@ -484,12 +486,12 @@ 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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fixDrawPattern(0, fixScaleUp(75), 0.05 * 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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fixDrawPattern(0, fixScaleUp(60), 0.05 * FIX,
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FP_PLASMA_DELAY, fixAnimPlasma, &r);
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#endif /* __AVR__ */
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}
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@ -505,9 +507,9 @@ void plasma(void)
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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_t fCos; /**< X-coordinate of the curl's center. */
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fixp_t fSin; /**< Y-coordinate of the curl's center. */
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fixp_t fPhaseShift; /**< Phase-shift for the flow effect. */
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} fixp_psychedelic_t;
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@ -530,15 +532,15 @@ static unsigned char fixAnimPsychedelic(unsigned char const x,
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if (x == 0 && y == 0)
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{
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p->fCos = NUM_COLS/2 * fixCos(t);
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p->fSin = NUM_ROWS/2 * fixSin(t);
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p->ft10 = fixMul(t, fixScaleUp(10));
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p->fCos = (fixp_t)(NUM_COLS * 0.72) * (fixCos(t) + FIX);
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p->fSin = (fixp_t)(NUM_ROWS * 0.72) * (fixSin(t) + FIX);
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p->fPhaseShift = t * 8;
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}
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unsigned char const nResult =
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(unsigned char)(fixMul(fixSin(fixDist(fixScaleUp(x), fixScaleUp(y),
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p->fCos, p->fSin) - p->ft10) + fixScaleUp(1),
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(fixp_t)((NUMPLANE - 1.05) * FIX))) / FIX;
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fixMul(fixSin(fixDist(fixScaleUp(x), fixScaleUp(y),
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p->fSin, p->fCos) - p->fPhaseShift) + FIX,
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(fixp_t)((NUMPLANE - 1.05) * FIX)) / FIX;
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assert(nResult <= NUMPLANE);
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return nResult;
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