From 360f07e4533d4ede7ba494724382fc8dbcb4649c Mon Sep 17 00:00:00 2001 From: Berthold Stoeger Date: Thu, 16 Aug 2018 19:10:10 +0200 Subject: Cleanup: pass gasmix by value In a previous commit, the get_gasmix_* functions were changed to return by value. For consistency, also pass gasmix by value. Note that on common 64-bit platforms struct gasmix is the size of a pointer [2 * 32 bit vs. 64 bit] and therefore uses the same space on the stack. On 32-bit platforms, the stack use is probably doubled, but in return a dereference is avoided. Supporting arbitrary gas-mixes (H2, Ar, ...) will be such an invasive change that going back to pointers is probably the least of our worries. This commit is a step in const-ifying input parameters (passing by value is the ultimate way of signaling that the input parameter will not be changed [unless there are references to said parameter]). Signed-off-by: Berthold Stoeger --- core/gas-model.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'core/gas-model.c') diff --git a/core/gas-model.c b/core/gas-model.c index 49c677967..7fb9ce111 100644 --- a/core/gas-model.c +++ b/core/gas-model.c @@ -26,7 +26,7 @@ * NOTE! Helium coefficients are a linear mix operation between the * 323K and one for 273K isotherms, to make everything be at 300K. */ -double gas_compressibility_factor(struct gasmix *gas, double bar) +double gas_compressibility_factor(struct gasmix gas, double bar) { static const double o2_coefficients[3] = { -7.18092073703e-04, @@ -69,15 +69,15 @@ double gas_compressibility_factor(struct gasmix *gas, double bar) /* Compute the new pressure when compressing (expanding) volome v1 at pressure p1 bar to volume v2 * taking into account the compressebility (to first order) */ -double isothermal_pressure(struct gasmix *gas, double p1, int volume1, int volume2) +double isothermal_pressure(struct gasmix gas, double p1, int volume1, int volume2) { double p_ideal = p1 * volume1 / volume2 / gas_compressibility_factor(gas, p1); return p_ideal * gas_compressibility_factor(gas, p_ideal); } -inline double gas_density(struct gasmix *gas, int pressure) { - int density = gas->he.permille * HE_DENSITY + gas->o2.permille * O2_DENSITY + (1000 - gas->he.permille - gas->o2.permille) * N2_DENSITY; +inline double gas_density(struct gasmix gas, int pressure) { + int density = gas.he.permille * HE_DENSITY + gas.o2.permille * O2_DENSITY + (1000 - gas.he.permille - gas.o2.permille) * N2_DENSITY; return density * (double) pressure / gas_compressibility_factor(gas, pressure / 1000.0) / SURFACE_PRESSURE / 1000000.0; } -- cgit v1.2.3-70-g09d2