X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;ds=sidebyside;f=drv%2Framp.c;fp=drv%2Framp.c;h=0000000000000000000000000000000000000000;hb=839bb85440ae6b21ef990fd373008a7a021a9148;hp=9a2cc92e446d7da6145811d3b123591ddb8000de;hpb=f3ba158c1ebfcef6c85759056d0a3d5f421ea870;p=bertos.git diff --git a/drv/ramp.c b/drv/ramp.c deleted file mode 100644 index 9a2cc92e..00000000 --- a/drv/ramp.c +++ /dev/null @@ -1,206 +0,0 @@ -/*! - * \file - * - * - * \brief Compute, save and load ramps for stepper motors (implementation) - * - * \version $Id$ - * - * \author Simone Zinanni - * \author Bernardo Innocenti - * \author Giovanni Bajo - * \author Daniele Basile - * - * - * The formula used by the ramp is the following: - * - * 
- *            a * b
- * f(t) = -------------
- *         lerp(a,b,t)
- *
- * - * Where a and b are the maximum and minimum speed - * respectively (minimum and maximum wavelength respectively), and lerp - * is a linear interpolation with a factor: - * - * 
- * lerp(a,b,t) =  a + t * (b - a)  =  (a * (1 - t)) + (b * t)
- *
- * - * t must be in the [0,1] interval. It is easy to see that the - * following holds true: - * - * 
- * f(0) = b,   f(1) = a
- *
- * - * And that the function is monotonic. So, the function effectively interpolates - * between the maximum and minimum speed through its domain ([0,1] -> [b,a]). - * - * The curve drawn by this function is similar to 1 / (sqrt(n)), so it is slower - * than a linear acceleration (which would be 1/n). - * - * The floating point version uses a slightly modified function which accepts - * the parameter in the domain [0, MT] (where MT is maxTime, the length of the - * ramp, which is a setup parameter for the ramp). This is done to reduce the - * number of operations per step. The formula looks like this: - * - * 
- *               a * b * MT
- * g(t) = ----------------------------
- *           (a * MT) + t * (b - a)
- *
- * - * It can be shown that this g(t) = f(t * MT). The denominator - * is a linear interpolation in the range [b*MT, a*MT], as t moves in the - * interval [0, MT]. So the interpolation interval of the function is again - * [b, a]. The implementation caches the value of the numerator and parts - * of the denominator, so that the formula becomes: - * - * 
- * alpha = a * b * MT
- * beta = a * MT
- * gamma = b - a
- *
- *                alpha
- * g(t) = ----------------------
- *           beta + t * gamma
- *
- * - * and t is exactly the parameter that ramp_evaluate() gets, - * that is the current time (in range [0, MT]). The operations performed - * for each step are just an addition, a multiplication and a division. - * - * The fixed point version of the formula instead transforms the original - * function as follows: - * - * 
- *                   a * b                         a
- *  f(t) =  -------------------------  =  --------------------
- *                 a                         a
- *           b * ( - * (1 - t) + t )         - * (1 - t) + t
- *                 b                         b
- *
- * - * t must be computed by dividing the current time (24 bit integer) - * by the maximum time (24 bit integer). This is done by precomputing the - * reciprocal of the maximum time as a 0.32 fixed point number, and multiplying - * it to the current time. Multiplication is performed 8-bits a time by - * FIX_MULT32(), so that we end up with a 0.16 fixed point number for - * t (and 1-t is just its twos-complement negation). - * a/b is in the range [0,1] (because a is always less than b, - * being the minimum wavelength), so it is precomputed as a 0.16 fixed point. - * The final step is then computing the denominator and executing the division - * (32 cycles using the 1-step division instruction in the DSP). - * - * The assembly implementation is needed for efficiency, but a C version of it - * can be easily written, in case it is needed in the future. - * - */ - -#include "ramp.h" -#include - -#include // memcpy() - -/** - * Multiply \p a and \p b two integer at 32 bit and extract the high 16 bit word. - */ -#define FIX_MULT32(a,b) (((uint64_t)(a)*(uint32_t)(b)) >> 16) - -void ramp_compute(struct Ramp *ramp, uint32_t clocksRamp, uint16_t clocksMinWL, uint16_t clocksMaxWL) -{ - ASSERT(clocksMaxWL >= clocksMinWL); - - // Save values in ramp struct - ramp->clocksRamp = clocksRamp; - ramp->clocksMinWL = clocksMinWL; - ramp->clocksMaxWL = clocksMaxWL; - -#if RAMP_USE_FLOATING_POINT - ramp->precalc.gamma = ramp->clocksMaxWL - ramp->clocksMinWL; - ramp->precalc.beta = (float)ramp->clocksMinWL * (float)ramp->clocksRamp; - ramp->precalc.alpha = ramp->precalc.beta * (float)ramp->clocksMaxWL; - -#else - ramp->precalc.max_div_min = ((uint32_t)clocksMinWL << 16) / (uint32_t)clocksMaxWL; - - /* Calcola 1/total_time in fixed point .32. Assumiamo che la rampa possa al - * massimo avere 25 bit (cioé valore in tick fino a 2^25, che con il - * prescaler=3 sono circa 7 secondi). Inoltre, togliamo qualche bit di precisione - * da destra (secondo quanto specificato in RAMP_CLOCK_SHIFT_PRECISION). - */ - ASSERT(ramp->clocksRamp < (1UL << (24 + RAMP_CLOCK_SHIFT_PRECISION))); - ramp->precalc.inv_total_time = 0xFFFFFFFFUL / (ramp->clocksRamp >> RAMP_CLOCK_SHIFT_PRECISION); - ASSERT(ramp->precalc.inv_total_time < 0x1000000UL); - -#endif -} - - -void ramp_setup(struct Ramp* ramp, uint32_t length, uint32_t minFreq, uint32_t maxFreq) -{ - uint32_t minWL, maxWL; - - minWL = TIME2CLOCKS(FREQ2MICROS(maxFreq)); - maxWL = TIME2CLOCKS(FREQ2MICROS(minFreq)); - - ASSERT2(minWL < 65536UL, "Maximum frequency too high"); - ASSERT2(maxWL < 65536UL, "Minimum frequency too high"); - ASSERT(maxFreq > minFreq); - - ramp_compute( - ramp, - TIME2CLOCKS(length), - TIME2CLOCKS(FREQ2MICROS(maxFreq)), - TIME2CLOCKS(FREQ2MICROS(minFreq)) - ); -} - -void ramp_default(struct Ramp *ramp) -{ - ramp_setup(ramp, RAMP_DEF_TIME, RAMP_DEF_MINFREQ, RAMP_DEF_MAXFREQ); -} - -#if RAMP_USE_FLOATING_POINT - -float ramp_evaluate(const struct Ramp* ramp, float curClock) -{ - return ramp->precalc.alpha / (curClock * ramp->precalc.gamma + ramp->precalc.beta); -} - -#else - -INLINE uint32_t fix_mult32(uint32_t m1, uint32_t m2) -{ - uint32_t accum = 0; - accum += m1 * ((m2 >> 0) & 0xFF); - accum >>= 8; - accum += m1 * ((m2 >> 8) & 0xFF); - accum >>= 8; - accum += m1 * ((m2 >> 16) & 0xFF); - return accum; -} - -// a*b >> 16 -INLINE uint16_t fix_mult16(uint16_t a, uint32_t b) -{ - return (b*(uint32_t)a) >> 16; -} - -uint16_t FAST_FUNC ramp_evaluate(const struct Ramp* ramp, uint32_t curClock) -{ - uint16_t t = FIX_MULT32(curClock >> RAMP_CLOCK_SHIFT_PRECISION, ramp->precalc.inv_total_time); - uint16_t denom = fix_mult16((uint16_t)~t + 1, ramp->precalc.max_div_min) + t; - uint16_t cur_delta = ((uint32_t)ramp->clocksMinWL << 16) / denom; - - return cur_delta; -} - -#endif - -