mk2: code_part1/OSTC_code_c_part2/p2

comparison code_part1/OSTC_code_c_part2/p2_deco.c @ 511:2a6293641d51

NEW NDL NDL faster/more precise simu (but no closed formula for trimix).

author	JeanDo
date	Fri, 25 Nov 2011 01:56:17 +0100
parents	103051b4d9c1
children	e7893664bd29

comparison

equal deleted inserted replaced

-:6c0bf50610f7
+:2a6293641d51
 // 2011/04/15: [jDG] Store low_depth in 32bits (w/o rounding), for a better stability.
 // 2011/04/25: [jDG] Added 1mn mode for CNS calculation, to allow it for decoplanning.
 // 2011/04/27: [jDG] Fixed char_O_gradient_factor calculation when model uses gradient-factor.
 // 2011/05/02: [jDG] Added "Future TTS" function (CF58).
 // 2011/05/17: [jDG] Various cleanups.
+// 2011/08/08: [jDG] Computes CNS during deco planning ascent.
+// 2011/11/24: [jDG] Slightly faster and better NDL computation.
 //
 // TODO:
 //  + Allow to abort MD2 calculation (have to restart next time).
 //
 // Literature:
 // preload tissues with standard pressure for the given ambient pressure.
 // Note: fixed N2_ratio for standard air.
 //
 static void clear_tissue(void)
 {
+overlay float p;
 	flag_in_divemode = 0;
 	int_O_DBS_bitfield = 0;
 	int_O_DBS2_bitfield = 0;
 	int_O_DBG_pre_bitfield = 0;
 	int_O_DBG_post_bitfield = 0;
 // Kludge: the 0.0002 of 0.7902 are missing with standard air.
 N2_ratio = 0.7902;
 pres_respiration = int_I_pres_respiration * 0.001;
+p = N2_ratio * (pres_respiration -  ppWater);
 for(ci=0; ci<NUM_COMP; ci++)
 {
-// cycle through the 16 Bühlmann tissues
+// cycle through the 16 Bühlmann N2 tissues
-overlay float p = N2_ratio * (pres_respiration -  ppWater);
 pres_tissue_N2[ci] = p;
 // cycle through the 16 Bühlmann tissues for Helium
 pres_tissue_He[ci] = 0.0;
-} // for 0 to 15
+}
 clear_deco_table();
 char_O_deco_status = 0;
 char_O_nullzeit = 0;
 int_O_ascenttime = 0;
 // Detect gas change condition.
 //
 void calc_hauptroutine_data_input(void)
 {
 overlay short int_temp;
+overlay unsigned char g;
 pres_respiration    = int_I_pres_respiration * 0.001;
 pres_surface        = int_I_pres_surface     * 0.001;
 N2_ratio            = char_I_N2_ratio        * 0.01;
 He_ratio            = char_I_He_ratio        * 0.01;
 // Keep a margin of 150mbar = 1.50m
 int_temp = (int_I_pres_respiration - int_I_pres_surface)
 + MBAR_REACH_GASCHANGE_AUTO_CHANGE_OFF;
-deco_gas_change[0] = 0;
-deco_gas_change[1] = 0;
-deco_gas_change[2] = 0;
-deco_gas_change[3] = 0;
-deco_gas_change[4] = 0;
 // Gas are selectable if we did not pass the change depth by more than 1.50m:
-if(char_I_deco_gas_change[0])
+for(g=0; g < NUM_GAS; ++g)
 {
-if( int_temp > 100 *(short)char_I_deco_gas_change[0] )
+deco_gas_change[g] = 0;
-	deco_gas_change[0] = char_I_deco_gas_change[0];
+if(char_I_deco_gas_change[g])
-}
+if( int_temp > 100 *(short)char_I_deco_gas_change[g] )
-if(char_I_deco_gas_change[1])
+	deco_gas_change[g] = char_I_deco_gas_change[g];
-{
-if( int_temp > 100 *(short)char_I_deco_gas_change[1] )
-	deco_gas_change[1] = char_I_deco_gas_change[1];
-}
-if(char_I_deco_gas_change[2])
-{
-if( int_temp > 100 *(short)char_I_deco_gas_change[2] )
-	deco_gas_change[2] = char_I_deco_gas_change[2];
-}
-if(char_I_deco_gas_change[3])
-{
-if( int_temp > 100 *(short)char_I_deco_gas_change[3] )
-	deco_gas_change[3] = char_I_deco_gas_change[3];
-}
-if(char_I_deco_gas_change[4])
-{
-if( int_temp > 100 *(short)char_I_deco_gas_change[4] )
-	deco_gas_change[4] = char_I_deco_gas_change[4];
 }
 const_ppO2 = char_I_const_ppO2 * 0.01;
 float_desaturation_multiplier = char_I_desaturation_multiplier * 0.01;
 float_saturation_multiplier   = char_I_saturation_multiplier   * 0.01;
 //////////////////////////////////////////////////////////////////////////////
 // calc_nullzeit
 //
 // calculates the remaining bottom time
 //
-// 2011-11-20 jDG: Changed (beta 2.06) to use Eric Baker's direct NDL formula.
+// NOTE: Erik Baker's closed formula works for Nitroxes. Trimix adds a second
+//       exponential term to the M-value equation, making it impossible to
+//       invert... So we have to make a fast-simu until we find a better way.
 //
 // Input:  pres_respiration
 // Output: char_O_nullzeit
 //
 static void calc_nullzeit(void)
 {
-overlay float Pin;
+//---- Compute ppN2 and ppHe ---------------------------------------------
 temp_deco = pres_respiration;
 sim_alveolar_presures();
-Pin = ppN2 + ppHe;
 char_O_nullzeit = 240;
 for(ci=0; ci<NUM_COMP; ci++)
 {
-//---- Compute composite A/B values and half times for the mix -------
+//---- Read A/B values and loading factor for N2 and He --------------
-overlay float N2 = pres_tissue_N2[ci];
+overlay float tN2 = pres_tissue_N2[ci];
-overlay float He = pres_tissue_He[ci];
+overlay float tHe = pres_tissue_He[ci];
-overlay float p = N2 + He;
+overlay float t = tN2 + tHe;
+overlay unsigned char ndl;
-read_buhlmann_ht();
+overlay unsigned char period = 10;
-var_N2_ht = (var_N2_ht * N2 + var_He_ht * He) / p;
 read_buhlmann_coefficients();
-var_N2_a = (var_N2_a * N2 + var_He_a * He) / p;
+read_buhlmann_times(2);             // Starts with a 10min period.
-var_N2_b = (var_N2_b * N2 + var_He_b * He) / p;
-//---- Calc time for that tissue -------------------------------------
+//---- Simulate for that tissue --------------------------------------
-// Erik Baker's formula:
+// NOTE: No need to simulate for longuer than the already found NDL.
-// M0 (M-value at surface) = var_N2_a + pres_surface/var_N2_b
+for(ndl=0; ndl<char_O_nullzeit;)
-// Pin = respirated pressure ppN2 + ppHe
+{
-// p   = pressure inside tissue
+//---- Compute updated mix M-value at surface
-// 0.6931 = log(2)
+overlay float a = (var_N2_a * tN2 + var_He_a * tHe) / t;
-// NDL(ci) = log((Pin - p)/(Pin - M0))/log(2) * ht
+overlay float b = (var_N2_b * tN2 + var_He_b * tHe) / t;
-//
+overlay float M0 = (a + pres_surface/b);
-if( Pin > p )   // Only when on-gasing
-{
+//---- Add 10min/1min to N2/He tissues
-overlay float M0 = (var_N2_a + pres_surface/var_N2_b);
+overlay float dTN2 = (ppN2 - tN2) * var_N2_e;
+overlay float dTHe = (ppHe - tHe) * var_He_e;
-// Apply security margin when using the GF model
-if( char_I_deco_model != 0 )
+//---- Apply security margin when using the non-GF model
+if( char_I_deco_model == 0 )
+{
+dTN2 *= float_saturation_multiplier;
+dTHe *= float_saturation_multiplier;
+}
+else // Or GF-based model
 M0 = GF_high * (M0 - pres_surface) + pres_surface;
-if( Pin > M0 )
+//---- Simulate off-gasing while going to surface
+// TODO !
+// dTN2 -= exp( ... ascent time ... ppN2...)
+// dTHe -= exp( ... ascent time ... ppHe...)
+//---- Still ok to surface after 1 or 10 minutes ?
+if( t + dTN2 + dTHe <= M0 )
 {
-overlay unsigned char indl;
+tN2 += dTN2;    // YES: apply gas loadings,
+tHe += dTHe;
-overlay float ndl = log((Pin - p)/(Pin - M0)) * var_N2_ht/0.6931;
+t = tN2 + tHe;
+ndl += period;  // increment NDL,
-// Apply non-GF model security margins:
+continue;       // and loop.
-// Saturation factor will be applied to gas loading, accelerating
-// loading, hence we should decrease NDL accordingly.
-if( char_I_deco_model == 0)
-ndl /= float_saturation_multiplier;
-if( ndl <   0.0f ) ndl = 0.0f;
-if( ndl > 254.5f ) ndl = 255.0f;
-indl = (unsigned char)(ndl + 0.5f);
-if( indl < char_O_nullzeit )
-char_O_nullzeit = indl;
 }
-}
+//---- Should we retry with smaller steps ?
+if( period == 10 )
+{
+read_buhlmann_times(1); // 1min coefs.
+period = 1;
+continue;
+}
+//---- ELSE make a linear approx for the last minute
+// Usefull to have a meneaingfull rounding of NDL
+ndl += (unsigned char)(0.5f + (M0-t)/(dTN2+dTHe));
+break;
+}
+// Keep the shortest NDL found
+if( ndl < char_O_nullzeit )
+char_O_nullzeit = ndl;
 }
 }
 //////////////////////////////////////////////////////////////////////////////
 // calc_ascenttime
 // Should be protected by deco_push_tissues_to_vault(),
 //                        deco_pull_tissues_from_vault()
 //
 // desaturation slowed down to 70,42%.
 //
-static void calc_dive_interval()
+static void calc_dive_interval(void)
 {
 overlay unsigned char t;
 overlay unsigned char backup_model;
 //---- Initialize simulation parameters ----------------------------------
 // Make sure SURFACE_DESAT_FACTOR is applyed:
 backup_model = char_I_deco_model;
 char_I_deco_model = 0;
 //---- Perform simulation ------------------------------------------------
 for(t=0; t<char_I_dive_interval; ++t)
 {
 calc_tissue(2);  // period = 10min.
 CNS_fraction =  0.92587471 * CNS_fraction;  // Half-time = 90min: (1/2)^(1/9)
 }
 }
 //////////////////////////////////////////////////////////////////////////////
 // deco_calc_CNS_planning
 //
-// Compute CNS during predicetd ascent.
+// Compute CNS during predicted ascent.
 //
 // Note:    Needs a call to deco_push_tissues_to_vault(),
 //          deco_pull_tissues_from_vault() to avoid trashing everything...
 //
 // Input:   CNS_fraction, char_O_deco_time[], char_O_deco_depth[]
 volumes[gas] = 65535.0;
 //---- Ascent usage ------------------------------------------------------
 deepest_first = read_custom_function(54) == 0;
-deco_usage  = (float) read_custom_function(57); // In liter/minutes.
+deco_usage    = (float) read_custom_function(57); // In liter/minutes.
 // Usage up to the first stop:
 //  - computed at MAX depth (easier, safer),
 //  - with an ascent speed of 10m/min.
 //  - with ascent litter / minutes.

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comparison code_part1/OSTC_code_c_part2/p2_deco.c @ 511:2a6293641d51