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.
Most of AP_Progmem is already gone so we can stop including it in most
of the places. The only places that need it are the ones using
pgm_read_*() APIs.
In some cases the header needed to be added in the .cpp since it was
removed from the .h to reduce scope. In those cases the headers were
also reordered.
Now variables don't have to be declared with PROGMEM anymore, so remove
them. This was automated with:
git grep -l -z PROGMEM | xargs -0 sed -i 's/ PROGMEM / /g'
git grep -l -z PROGMEM | xargs -0 sed -i 's/PROGMEM//g'
The 2 commands were done so we don't leave behind spurious spaces.
AVR-specific places were not changed.
The PSTR is already define as a NOP for all supported platforms. It's
only needed for AVR so here we remove all the uses throughout the
codebase.
This was automated with a simple python script so it also converts
places which spans to multiple lines, removing the matching parentheses.
AVR-specific places were not changed.
Remove unnecessary includes, in particular the includes for specific
boards. The list of libraries for 'polygon' example was updated so that
the example compiles again.
Instead of requiring every program to specify the HAL related modules,
let the build system do it (in practice everything we compiled depended
on HAL anyway). This allow including only the necessary files in the
compilation.
The switching between different AP_HAL was happening by giving different
definitions of AP_HAL_BOARD_DRIVER, and the programs would use it to
instantiate.
A program or library code would have to explicitly include (and depend)
on the concrete implementation of the HAL, even when using it only via
interface.
The proposed change move this dependency to be link time. There is a
AP_HAL::get_HAL() function that is used by the client code. Each
implementation of HAL provides its own definition of this function,
returning the appropriate concrete instance.
Since this replaces the job of AP_HAL_BOARD_DRIVER, the definition was
removed.
The static variables for PX4 and VRBRAIN were named differently to avoid
shadowing the extern symbol 'hal'.
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.
This commit changes the way libraries headers are included in source files:
- If the header is in the same directory the source belongs to, so the
notation '#include ""' is used with the path relative to the directory
containing the source.
- If the header is outside the directory containing the source, then we use
the notation '#include <>' with the path relative to libraries folder.
Some of the advantages of such approach:
- Only one search path for libraries headers.
- OSs like Windows may have a better lookup time.
This commit changes the way libraries headers are included in source files:
- If the header is in the same directory the source belongs to, so the
notation '#include ""' is used with the path relative to the directory
containing the source.
- If the header is outside the directory containing the source, then we use
the notation '#include <>' with the path relative to libraries folder.
Some of the advantages of such approach:
- Only one search path for libraries headers.
- OSs like Windows may have a better lookup time.
Tom Pittenger
Lucas De Marchi
Gustavo Jose de Sousa
Caio Marcelo de Oliveira Filho
Andrew Tridgell
José Roberto de Souza
Randy Mackay
Valmantas Palikša
Siddharth Bharat Purohit
Jonathan Challinger