ST视觉开发中调试变量错误

sqrt（）是否使用双打？
你想要sqrtf（）吗？
它是在寄存器中保存值/变量而不是内存吗？堆栈框架在移动吗？
您应该查看与该函数相关的汇编代码。理想情况下，如果编译器生成这样的代码/汇编器列表类型文件。
不确定这里有多少STM8支持。
//这可能有更好的施法
result =（uint16_t）（（sqrt（（double）sum /（double）measures_nb）/ 1023.0 * 3.3 / 0.1）* 1000.0）;
您还可以将值保存为double并首先检查。还要考虑使用测试值检查/调试PC编译器。



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Isn't sqrt() using doubles?  
Do you want sqrtf() ?
Is it holding values/variables in registers and not memory? Is the stack frame moving?
You should review the assembler code related with the function. Ideally a code/assembler listing type file if the compiler generates such.
Not sure there is much STM8 support to be had here.
// This might have better casting
result = (uint16_t)((sqrt((double)sum / (double)measures_nb) / 1023.0 * 3.3 / 0.1) * 1000.0);
You could also save the values as a double and check that first. Consider also checking/debugging on a PC compiler with test values.

sqrt（）是否使用双打？
是的。使用float而不是double会发生什么问题？
它是在寄存器中保存值/变量而不是内存吗？堆栈框架在移动吗？
我明天会检查这个，但你能解释一下你想知道什么，你正在谈论什么价值，因为我不是汇编，注册，...的专家。
谢谢



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Isn't sqrt() using doubles?   
Yes it is. What wrong could happen by using a float instead of a double ?
Is it holding values/variables in registers and not memory? Is the stack frame moving?
I will check this tomorrow but can you explain a little bit more what you want to know and what values you are talking about because i'm not an expert with assembler, register,  ...
Thanks

float / double的选择很大程度上取决于数字和精度的范围，以及你想要进行计算的速度。
如果你可以保持一种形式而不是来回转换，那将节省大量时间。将常量保持为一种形式，并让编译器折叠数学。
result =（uint16_t）（（sqrtf（（float）sum /（float）measures_nb）/ 1023.0f * 3.3f / 0.1f）* 1000.0f）;
抱歉，对STM8及其编译器/调试器没有任何特定的经验。如果将变量保存在寄存器而不是存储器中，则变量的可见性可能会受到限制。你必须阅读代码来衡量它在做什么



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The choice of float/double depends a lot on the range of numbers and precision, and the speed at which you want to do the computations.
If you can stay in one form and not convert back-and-forth, that would save a lot of time. As will keeping the constants in one form, and having the compiler fold up the math.
result = (uint16_t)((sqrtf((float)sum / (float)measures_nb) / 1023.0f * 3.3f / 0.1f) * 1000.0f);
Sorry don't have any specific experience with the STM8 and its compiler/debugger. Visibility of variables may be limited if they are held in registers rather than memory. You'll have to read the code to gauge what it is doing

你好，
在Cosmic stm8编译器中，双精度数被静默转换为float，因为它没有为此微实现实现double，因为它会使用太多资源。
对于未按预期显示的变量值，原因可能与Clive所说的一样：在某些点上，变量可能保存在寄存器或堆栈中，调试信息并不总是能够遵循这一点，在调试时会产生一些混乱。通常将变量声明为volatile是足以使它们正确显示，但这是一种肮脏的解决方法，您应该在检查值时删除关键字。
至于计算错误的结果，它可能与浮点数的精度有关：只是为了给你一个想法，浮点类型具有大约7个有用数字的精度，因此如果你的计算（或一些它的中间结果）需要更多的计算可能会出错：如果您使用更大的类型进行相同的计算（在PC上或实际实现双重类型的更大的微型），您将看到差异。
问候，
卢卡



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Hello,
in the Cosmic stm8 compiler doubles are silently converted to float, since double is not implemented for this micro as it would use too many resources.
For the values of variables not showing as you would expect, the reason is probably as Clive says: in some points variables might be held in registers or stack and the debug info is not always able to follow this, generating some confusion when you debug. Usually declaring the variables as volatile is enough to make them display correctly, but this is a dirty workaround, and you should remove the keyword when you have checked your values.
As for the result of the calculation being wrong, it has probably something to do with the precison of the float: just to give you an idea, the float type has a precision of around 7 useful digits, therefore if your calculation (or some of its interlmediate results) requires more the calculation might go wrong: if you do the same calculation with bigger types (on a PC or on a bigger micro where the double type is actually implemented) you will see the difference.
Regards,
Luca

在Cosmic stm8编译器中，双精度数被静默转换为float，因为它没有为此微实现实现double，因为它会使用太多资源。
目前STM8的所有编译器（SDCC，IAR，Cosmic，Raisonance）都将使用float而不是double。有些人默默地（至少是宇宙），有些人有警告（至少是SDCC）。
菲利普



以下为原文



in the Cosmic stm8 compiler doubles are silently converted to float, since double is not implemented for this micro as it would use too many resources.
Currently all compilers (SDCC, IAR, Cosmic, Raisonance) for the STM8 will use float instead of double. Some silently (at least Cosmic), others with a warning (at least SDCC).
Philipp