i2c smbus过滤器函数损坏变量 [英] i2c smbus filter function corrupting variables
问题描述
我有一个简单的函数
#define AMB_FILTER 0.7f
int32_t fValue; (this is declared in the class header)
int32_t Ambient::filter(uint32_t raw)
{
// If we have no preliminary fValue we don't need to calculate a filter
if(fValue == -1)
{
fValue = raw;
return fValue;
}
float y, yy;
y = (1.0f - AMB_FILTER) * (float) raw;
yy = AMB_FILTER * (float) fValue;
fValue = (int32_t) (y + yy);
printf("filter raw %d y %f yy %f fValue %d\n",raw, y, yy, fValue);
return fValue;
}
它接收从smbus ,并返回使用接收到的最后一个值过滤的值。这是它从printf语句的输出
It takes in a value that was read from smbus and returns a value that was filtered with the last value it received. Here is its output from the printf statement
filter raw 454 y 136.200012 yy 317.799988 fValue 454
filter raw 454 y 136.200012 yy 317.799988 fValue 454
filter raw 454 y 136.200012 yy 317.799988 fValue 454
filter raw 455 y 136.500000 yy 317.799988 fValue 454
filter raw 455 y 136.500000 yy 317.799988 fValue 454
filter raw 455 y 136.500000 yy 317.799988 fValue 454
filter raw 455 y 136.500000 yy 317.799988 fValue 454
filter raw 455 y 136.500000 yy 317.799988 fValue 454
filter raw 454 y 136.200012 yy 317.799988 fValue 454
filter raw 455 y 136.500000 yy -731751040.000000 fValue -731750912
filter raw 455 y 136.500000 yy -512225632.000000 fValue -512225504
filter raw 455 y 136.500000 yy -358557856.000000 fValue -358557728
filter raw 455 y 136.500000 yy -250990400.000000 fValue -250990256
filter raw 454 y 136.200012 yy -175693184.000000 fValue -175693040
发生什么事?它是如何仍然收到相同的输入,但突然变得疯狂?我不设置fValue在任何地方,但这个功能。
So what is happening? How is it that it still received the same input but all of a sudden went crazy? I don't set the fValue anywhere but this function.
我使这些变量(y和yy)非常内在的函数,因为我担心他们不知何故被修改或与其他东西碰撞。但现在,他们是完全地方我不知道发生了什么。我使用C ++类,所以这应该都在自己的空间无论如何。
I made these variables (y and yy) very internalized to the function because I was worried they were somehow being modified or collided with something else. But now that they are completely local I have no idea what is happening. I am using C++ classes so this should all be in its own space anyhow.
编辑:事实上,如果我让它运行一个更长的变量,我保持为不同i2c芯片地址也被损坏为-1075766188。到底是什么?
In fact if I let it run a little longer the variables I keep for the different i2c Chip addresses also become corrupted to -1075766188. What the hell?
推荐答案
[t1] filter raw 454 y 136.200012 yy 317.799988 fValue 454
[t2] filter raw 455 y 136.500000 yy -731751040.000000 fValue -731750912
t1 和 t2 之间的 fValue
已损坏。 yy
的损坏是 fValue
损坏的结果。在你的程序中的别处查找罪魁祸首。
Sometime between t1 and t2 the value of fValue
was corrupted. The corruption of yy
is a consequence of fValue
's corruption. Look elsewhere in your program for the culprit.
- 如果您不能使用
valgrind
fvalue
。 - 在您的例程中打印
。
- 从
Ambient
中打印其他成员变量的值。看看他们是否不寻常。 - 尝试注释大量的代码。从你的程序的1/2开始。如果bug仍然存在,注释掉剩余的1/2。
- If you can't use
valgrind
, then sprinkle sanity checks on the valueoffvalue
throughout your program. - Print the value of
this
in your routine. See if it becomes unusual. - Print the value of other member variables from
Ambient
. See if they become unusual. - Try commenting out huge tracts of code. Start with 1/2 of your program. If the bug is still there, comment out 1/2 of the remainder. Continue until you find a single line that controls the corruption.
至于它是如何损坏的,有很多种可能性。也许你在某个地方引用一个野生指针。也许你写超出数组的末尾。也许你正在使用以前销毁的环境
。
As to how it was corrupted, there are many possibilities. Perhaps you dereference a wild pointer somewhere. Perhaps you write beyond the end of an array. Perhaps you are operating on a previously destroyed Ambient
.
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