The new function can deal with a variable number of function parameters.
Additionally, I renamed the functions to norm(), because this is the
standard name used in several other projects.
The problem with the current MIN/MAX macros is that they evaluate twice
the arguments. For example, these cases provide unintended results:
// a is incremented twice
a = MIN(a++, b);
// foo() with side-effects
a = MIN(foo(), b);
The alternative implementation here was provided by Daniel Frenzel using
template function. It doesn't have type safety as std::min and std::max,
but adding type safety would mean to check case by case what would be a
reasonable type and add proper casts. Here the arguments for MIN and MAX
can have different types and the return type is deduced from the
expression in the function.
Inspecting the current callers no place was found with the unintended
results above, but some in which now we don't calculate twice the
parameters will benefit from this new version. Examples:
float velocity_max = MIN(_pos_control.get_speed_xy(), safe_sqrt(0.5f*_pos_control.get_accel_xy()*_radius));
float acro_level_mix = constrain_float(1-MAX(MAX(abs(roll_in), abs(pitch_in)), abs(yaw_in))/4500.0, 0, 1)*ahrs.cos_pitch()
accel_x_cmss = (GRAVITY_MSS * 100) * (-(_ahrs.cos_yaw() * _ahrs.sin_pitch() / MAX(_ahrs.cos_pitch(),0.5f)) - _ahrs.sin_yaw() * _ahrs.sin_roll() / MAX(_ahrs.cos_roll(),0.5f));
track_leash_slack = MIN(_track_leash_length*(leash_z-track_error_z)/leash_z, _track_leash_length*(leash_xy-track_error_xy)/leash_xy);
RC_Channel_aux::move_servo(RC_Channel_aux::k_sprayer_pump, MIN(MAX(ground_speed * _pump_pct_1ms, 100 *_pump_min_pct),10000),0,10000);
The problem with using min() and max() is that they conflict with some
C++ headers. Name the macros in uppercase instead. We may go case by
case later converting them to be typesafe.
Changes generated with:
git ls-files '*.cpp' '*.h' -z | xargs -0 sed -i 's/\([^_[:alnum:]]\)max(/\1MAX(/g'
git ls-files '*.cpp' '*.h' -z | xargs -0 sed -i 's/\([^_[:alnum:]]\)min(/\1MIN(/g'
Remove the checks for HAL_CPU_CLASS > HAL_CPU_CLASS_16 and
HAL_CPU_CLASS >= HAL_CPU_CLASS_75. Corresponding dead code will be
removed on separate commits.
compile time optimization
Functions like sq() are better moved to the header file as inline.
Compiler can then optimize these out when used in code, this saves cpu
cycles with stack push, pop during function calls.
Peter Barker
Miguel Arroyo
Francisco Ferreira
Michael du Breuil
Andrew Tridgell
Pierre Kancir
Lucas De Marchi
dgrat
Ricardo de Almeida Gonzaga
Daniel Frenzel
bugobliterator
José Roberto de Souza
Jonathan Challinger
Tom Pittenger
Valmantas Palikša