CANpack code generation Problem for MCU without floating-point math capabilities

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zhichao li
zhichao li 2023-9-16
回答： zhichao li 2023-9-17
real32_T outValue = 0;
{
real32_T result =aa;
result =bb;
outValue = roundf(result);
"This facility may not be available on configurations of the EWL that run on platforms
that do not have floating-point math capabilities. "
--EWL C Reference Manual.pdf

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Walter Roberson
Walter Roberson 2023-9-17
编辑：Walter Roberson 2023-9-17

roundf has been part of the C standard library since C99. However it expects floating point input and returns floating point output, which is a problem if you are using a system that does not have floating point hardware.

On a system that does not have floating point hardware, you have two choices:

  • you can carefully write your code to only operate on the int* and uint* classes; or
  • you can convert your code to use fixed-point arithmetic with the Fixed-Point Toolbox. The fixed point toolbox can emulate many floating-point operations in software, including potentially to greater precision than double precision floating point. However, transcendental functions such as trig functions or log generally have to be rewritten; search for CORDIC for those.
  1 个评论
zhichao li
zhichao li 2023-9-17
thanks!
use fixed-point arithmetic is a good solution,I will test!
now I just delete the roundf, Refer to older versions of code generation(15b)

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zhichao li
zhichao li 2023-9-17
I solved it by modify the function in can_helpers.tlc
%function roundRealValue(inVar, outVar, dataType)
%openfile buffer
%switch dataType
%case "real32_T"
%% %<outVar> = roundf(%<inVar>); //before
%<outVar> = %<inVar>;
%break
%case "real_T"
%case "real64_T"
%% %<outVar> = round(%<inVar>); //before
%<outVar> = %<inVar>;
%break
%endswitch
%closefile buffer
%return buffer
%endfunction

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