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fpmath_patterns.c: fixed some bugs which made the higher precision mode 

unusable; animations look slightly different, now
feature/2015
Christian Kroll 11 years ago
parent
3a5052900d
commit
1dff4f3885
1 changed files with 54 additions and 52 deletions
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  1. 106
      src/animations/fpmath_patterns.c

106
src/animations/fpmath_patterns.c
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@ -20,18 +20,20 @@
#ifdef DOXYGEN
/**
* Low precision means that we use Q10.5 values and 16 bit types for almost
* every calculation (with multiplication and division as notable exceptions
* as they and their interim results utilize 32 bit).
* Low precision means that we use Q9.6 values and 16 bit types for almost
* every calculation (with multiplication being a notable exception as its
* interim results utilize 32 bit types).
*
* Use this precision mode with care as image quality will suffer
* noticeably. It produces leaner and faster code, though. This mode should
* not be used with resolutions higher than 16x16 as overflows are likely to
* occur in interim calculations.
* Use this precision mode with care as image quality will suffer noticeably
* at higher resolutions. This mode should not be used with resolutions
* higher than 16x16 as overflows are likely to occur in interim
* calculations. It produces leaner and faster code, though.
*
* Normal precision (i.e. #undef LOW_PRECISION) conforms to Q7.8 with the
* ability to store every interim result as Q23.8. Most operations like
* square root, sine, cosine, multiplication etc. utilize 32 bit types.
* Normal precision (i.e. #undef LOW_PRECISION) conforms to Q23.8 for actual
* values and interim results. Operations like square root, sine, cosine,
* multiplication etc. utilize 32 bit types. It's extremly slow on AVR, but
* it's your only chance to run those animations on devices with resolutions
* higher than 16x16.
*/
#define FP_LOW_PRECISION
#endif /* DOXYGEN */
@ -66,18 +68,18 @@
// lookup table as well!
/** Multiply a number by this factor to convert it to a fixed-point value.*/
#define FIX 32
#define FIX 64
/** Number of fractional bits of a value (i.e. ceil(log_2(FIX))). */
#define FIX_FRACBITS 5
#define FIX_FRACBITS 6
/**
* The number of temporal quantization steps of the sine lookup table. It
* must be a divisor of (FIX * 2 * pi) and this divisor must be divisable by
* 4 itself. Approximate this value as close as possible to keep rounding
* errors at a minimum.
*/
#define FIX_SIN_COUNT 200
#define FIX_SIN_COUNT 200u
/** The rounded down quotient of (FIX * 2 * pi) and FIX_SIN_COUNT */
#define FIX_SIN_DIVIDER 1
#define FIX_SIN_DIVIDER 2u
/** Type of the lookup table elements. */
typedef uint8_t lut_t;
@ -85,26 +87,26 @@
/**
* Lookup table of fractional parts which model the first quarter of a
* sine period. The rest of that period is calculated by mirroring those
* values. These values are intended for Q5 types.
* values. These values are intended for Q6 types.
*/
static lut_t const fix_sine_lut[FIX_SIN_COUNT / 4] =
{ 0, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 14,
15, 16, 17, 18, 19, 20, 20, 21,
22, 23, 23, 24, 25, 25, 26, 26,
27, 27, 28, 28, 29, 29, 30, 30,
30, 31, 31, 31, 31, 32, 32, 32,
32, 32};
{ 0, 2, 4, 6, 8, 10, 12, 14,
16, 18, 20, 22, 24, 25, 27, 29,
31, 33, 34, 36, 38, 39, 41, 42,
44, 45, 47, 48, 49, 51, 52, 53,
54, 55, 56, 57, 58, 59, 60, 60,
61, 61, 62, 62, 63, 63, 63, 64,
64, 64};
#else
/** This is the type we expect ordinary integers to be. */
typedef int16_t ordinary_int_t;
/** This is the type which we use for fixed-point values. */
typedef int16_t fixp_t;
typedef int32_t fixp_t;
/** This type covers arguments of fixSin() and fixCos(). */
typedef int32_t fixp_trig_t;
/** This type covers interim results of fixed-point operations. */
typedef int32_t fixp_interim_t;
typedef uint32_t fixp_interim_t;
/** This type covers interim results of the fixSqrt() function. */
typedef uint32_t ufixp_interim_t;
/** Number of bits the fixSqrt() function can handle. */
@ -123,12 +125,12 @@
* 4 itself. Approximate this value as close as possible to keep rounding
* errors at a minimum.
*/
#define FIX_SIN_COUNT 200
#define FIX_SIN_COUNT 200u
/** The rounded down quotient of (FIX * 2 * pi) and FIX_SIN_COUNT */
#define FIX_SIN_DIVIDER 8
#define FIX_SIN_DIVIDER 8u
/** Type of the lookup table elements. */
typedef uint8_t lut_t;
typedef int16_t lut_t;
/**
* Lookup table of fractional parts which model the first quarter of a
@ -142,7 +144,7 @@
175, 181, 186, 192, 197, 202, 207, 211,
216, 220, 224, 228, 231, 235, 238, 240,
243, 245, 247, 249, 251, 252, 253, 254,
255, 255};
255, 256};
#endif
@ -252,14 +254,14 @@ static fixp_t fixSin(fixp_trig_t fAngle)
/**
* Fixed-point variant of the cosine function which takes a fixed-point angle
* (radian). It adds FIX_PI_2 to the given angle and consults the fixSin()
* function for the final result.
* (radian). It substracts FIX_PI_2 from the given angle and consults the
* fixSin() function for the final result.
* @param fAngle A fixed-point value in radian.
* @return Result of the cosine function normalized to a range from -FIX to FIX.
*/
static fixp_t fixCos(fixp_trig_t const fAngle)
static inline fixp_t fixCos(fixp_trig_t const fAngle)
{
return fixSin(fAngle + FIX_PI_2);
return fixSin(fAngle - FIX_PI_2);
}
@ -275,11 +277,11 @@ static fixp_t fixSqrt(ufixp_interim_t const a)
nRoot = 0; // clear root
nRemainingHigh = 0; // clear high part of partial remainder
nRemainingLow = a; // get argument into low part of partial remainder
nCount = (SQRT_BITS / 2 - 1) + (FIX_FRACBITS >> 1); // load loop counter
nCount = ((SQRT_BITS - 1) + FIX_FRACBITS) / 2; // load loop counter
do
{
nRemainingHigh =
(nRemainingHigh << 2) | (nRemainingLow >> (SQRT_BITS - 2));
(nRemainingHigh << 2) | (nRemainingLow >> (SQRT_BITS - 2));
nRemainingLow <<= 2; // get 2 bits of the argument
nRoot <<= 1; // get ready for the next bit in the root
nTestDiv = (nRoot << 1) + 1; // test radical
@ -451,16 +453,16 @@ static unsigned char fixAnimPlasma(unsigned char const x,
assert(x < (LINEBYTES * 8));
assert(y < NUM_ROWS);
// scaling factor
static fixp_t const fPlasmaX = (2 * PI * FIX) / NUM_COLS;
// reentrant data
fixp_plasma_t *const p = (fixp_plasma_t *)r;
// scaling factor
static fixp_t const fPlasmaX = FIX / 3.7;
if (x == 0 && y == 0)
{
p->fFunc2CosArg = NUM_ROWS * fixCos(t) + fixScaleUp(NUM_ROWS);
p->fFunc2SinArg = NUM_COLS * fixSin(t) + fixScaleUp(NUM_COLS);
p->fFunc2CosArg = NUM_COLS * (fixCos(t) + FIX);
p->fFunc2SinArg = NUM_ROWS * (fixSin(t) + FIX);
for (unsigned char i = LINEBYTES * 8u; i--;)
{
p->fFunc1[i] = fixSin(fixMul(fixScaleUp(i), fPlasmaX) + t);
@ -470,8 +472,8 @@ static unsigned char fixAnimPlasma(unsigned char const x,
fixp_t const fFunc2 = fixSin(fixMul(fixDist(fixScaleUp(x), fixScaleUp(y),
p->fFunc2SinArg, p->fFunc2CosArg), fPlasmaX));
unsigned char const nRes = (unsigned char)(fixMul(p->fFunc1[x] + fFunc2 +
fixScaleUp(2), ((NUMPLANE + 1) / 4.0 - 0.05) * FIX)) / FIX;
unsigned char const nRes = (fixMul(p->fFunc1[x] + fFunc2 +
2 * FIX, ((NUMPLANE + 1) / 4.0 - 0.05) * FIX)) / FIX;
assert (nRes <= NUMPLANE);
return nRes;
@ -484,12 +486,12 @@ void plasma(void)
{
fixp_plasma_t r;
#ifndef __AVR__
fixDrawPattern(0, fixScaleUp(75), 0.1 * FIX, 15, fixAnimPlasma, &r);
fixDrawPattern(0, fixScaleUp(75), 0.05 * FIX, 15, fixAnimPlasma, &r);
#else
#ifndef FP_PLASMA_DELAY
#define FP_PLASMA_DELAY 1
#endif
fixDrawPattern(0, fixScaleUp(60), 0.1 * FIX,
fixDrawPattern(0, fixScaleUp(60), 0.05 * FIX,
FP_PLASMA_DELAY, fixAnimPlasma, &r);
#endif /* __AVR__ */
}
@ -505,9 +507,9 @@ void plasma(void)
*/
typedef struct fixp_psychedelic_s
{
fixp_t fCos; /**< One of the column factors of the curl. */
fixp_t fSin; /**< One of the row factors of the curl. */
fixp_interim_t ft10; /**< A value involved in rotating the curl's center. */
fixp_t fCos; /**< X-coordinate of the curl's center. */
fixp_t fSin; /**< Y-coordinate of the curl's center. */
fixp_t fPhaseShift; /**< Phase-shift for the flow effect. */
} fixp_psychedelic_t;
@ -530,15 +532,15 @@ static unsigned char fixAnimPsychedelic(unsigned char const x,
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));
p->fCos = (fixp_t)(NUM_COLS * 0.72) * (fixCos(t) + FIX);
p->fSin = (fixp_t)(NUM_ROWS * 0.72) * (fixSin(t) + FIX);
p->fPhaseShift = t * 8;
}
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;
fixMul(fixSin(fixDist(fixScaleUp(x), fixScaleUp(y),
p->fSin, p->fCos) - p->fPhaseShift) + FIX,
(fixp_t)((NUMPLANE - 1.05) * FIX)) / FIX;
assert(nResult <= NUMPLANE);
return nResult;

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