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leon de boer wrote: Again I say if we know what CPU we are dealing with it is easier to make more detailed and helpful suggestions.
Single core (STM32F4 and STM32F7). Since I'm working with rather basic microcontrollers and my applications really aren't that heavy, it's seems a bit overkill to do the context switching like an RTOS would do.
modified 11-Jun-18 9:21am.
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There is actually less code in writing the switcher it's a couple hundred lines of code and it's faster as your CPU is designed to context switch 
From "The Definitive Guide to ARM Cortex M3 and Cortex-M4" that is a 4 task round robin switcher in 150 lines of code.
You just need to change the scheduler (SysTick_Handler) to a priority based one .. you will find dozens on the net
You can extend the number of task etc, the code is very very obvious and easier than your current scheme you have reached.
#include "stm32f4xx.h"
#define LED0 (1<<7)
#define LED1 (1<<8)
#define LED2 (1<<9)
#define LED3 (1<<10)
#define HW32_REG(ADDRESS) (*((volatile unsigned long *)(ADDRESS)))
#define stop_cpu __breakpoint(0)
void LED_initialize(void);
void task0(void);
void task1(void);
void task2(void);
void task3(void);
volatile uint32_t systick_count=0;
long long task0_stack[1024], task1_stack[1024],
task2_stack[1024], task3_stack[1024];
uint32_t curr_task=0;
uint32_t next_task=1;
uint32_t PSP_array[4];
int main(void)
{
SCB->CCR |= SCB_CCR_STKALIGN_Msk;
LED_initialize();
PSP_array[0] = ((unsigned int) task0_stack)
+ (sizeof task0_stack) - 16*4;
HW32_REG((PSP_array[0] + (14<<2))) = (unsigned long) task0;
HW32_REG((PSP_array[0] + (15<<2))) = 0x01000000;
PSP_array[1] = ((unsigned int) task1_stack)
+ (sizeof task1_stack) - 16*4;
HW32_REG((PSP_array[1] + (14<<2))) = (unsigned long) task1;
HW32_REG((PSP_array[1] + (15<<2))) = 0x01000000;
PSP_array[2] = ((unsigned int) task2_stack)
+ (sizeof task2_stack) - 16*4;
HW32_REG((PSP_array[2] + (14<<2))) = (unsigned long) task2;
HW32_REG((PSP_array[2] + (15<<2))) = 0x01000000;
PSP_array[3] = ((unsigned int) task3_stack)
+ (sizeof task3_stack) - 16*4;
HW32_REG((PSP_array[3] + (14<<2))) = (unsigned long) task3;
HW32_REG((PSP_array[3] + (15<<2))) = 0x01000000;
curr_task = 0;
__set_PSP((PSP_array[curr_task] + 16*4));
NVIC_SetPriority(PendSV_IRQn, 0xFF);
SysTick_Config(168000);
__set_CONTROL(0x3);
__ISB();
task0();
while(1){
stop_cpu;
};
}
void task0(void)
{ while (1) {
if (systick_count & 0x80) {GPIOE->BSRRL = LED0;}
else {GPIOE->BSRRH = LED0;}
};
}
void task1(void)
{ while (1) {
if (systick_count & 0x100){GPIOE->BSRRL = LED1;}
else {GPIOE->BSRRH = LED1;}
};
}
void task2(void)
{ while (1) {
if (systick_count & 0x200){GPIOE->BSRRL = LED2;}
else {GPIOE->BSRRH = LED2;}
};
}
void task3(void)
{ while (1) {
if (systick_count & 0x400){GPIOE->BSRRL = LED3;}
else {GPIOE->BSRRH = LED3;}
};
}
__asm void PendSV_Handler(void)
{
MRS R0, PSP
STMDB R0!,{R4-R11}
LDR R1,=__cpp(&curr_task)
LDR R2,[R1]
LDR R3,=__cpp(&PSP_array)
STR R0,[R3, R2, LSL #2]
LDR R4,=__cpp(&next_task)
LDR R4,[R4]
STR R4,[R1]
LDR R0,[R3, R4, LSL #2]
LDMIA R0!,{R4-R11}
MSR PSP, R0
BX LR
ALIGN 4
}
void SysTick_Handler(void)
{
systick_count++;
switch(curr_task) {
case(0): next_task=1; break;
case(1): next_task=2; break;
case(2): next_task=3; break;
case(3): next_task=0; break;
default: next_task=0;
stop_cpu;
break;
}
if (curr_task!=next_task){
SCB->ICSR |= SCB_ICSR_PENDSVSET_Msk;
}
return;
}
void LED_initialize(void)
{
RCC->AHB1ENR |= RCC_AHB1ENR_GPIOEEN;
GPIOE->MODER |= (GPIO_MODER_MODER7_0 |
GPIO_MODER_MODER8_0 |
GPIO_MODER_MODER9_0 |
GPIO_MODER_MODER10_0 ) ;
GPIOE->OSPEEDR |= (GPIO_OSPEEDER_OSPEEDR7 |
GPIO_OSPEEDER_OSPEEDR8 |
GPIO_OSPEEDER_OSPEEDR9 |
GPIO_OSPEEDER_OSPEEDR10 );
GPIOE->PUPDR = 0;
return;
}
In vino veritas
modified 11-Jun-18 10:49am.
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Thank you for your very elaborate answers.
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I've done cooperative multitaskers on a number of platforms (not ARM, but I don't think it should present any unusual problems) and found them to be extremely handy in cases where the set of tasks is fixed. Even if a task would spend most of its time in a loop:
while(!x_ready)
task_spin();
the cost to switch to the task, check x_ready, and then switch to the next task may be less than the cost of a more complicated scheduler trying to decide if it should switch to that task.
The biggest design issue with a cooperative task switcher is deciding what invariants are going to hold any time code does a task_spin(). While a preemptive multitasker would require that functions acquire locks before breaking any invariant even temporarily, and re-establish the invariant before releasing the lock, cooperative task switching doesn't require that. More significantly, it doesn't require that tasks do anything special to handle the fact that a lock isn't available. The gotcha is that if an invariant can't be upheld during some operation, and the time required to perform that operation could grow beyond the maximum amount of time one wants to go without a task_spin(), handling that situation may be complicated.
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String Area = AreaCBox.Text;
DAL.CaseBarCode csbrt = new DAL.CaseBarCode();
System.Data.DataSet csbrs = csbrt.GetPO(Area);
foreach (DataRow dr in csbrs.Tables[0].Rows)
{
POCBox.Items.Add(dr["ProductionOrder"]);
}
Hello,
In the above the code I am calling a stored procedure(csbrt.GetPO(Area)) which retrieves two values "ProductionOrder" and "colorflag" columns. I am inserting ProductionOrder into 'POCBox' combobox.
Now my requirement is to color the text for ProductionOrder in the combobox to green if the colorflag value is 0 and color it red if the colorflag value is 1. Please help with the code. Thanks in advance.
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What you want is called an "owner drawn" combobox.
There's a great article right here on CP that explains how to do it with all the code you need:
Implementing an OwnerDrawn ComboBox[^]
And by the way, you posted this in the C++ forum instead of the C# forum where it belongs.
The difficult we do right away...
...the impossible takes slightly longer.
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#include <iostream>
using namespace std;
template <class T>
class Num {
protected:
T val;
public:
Num(T x) { val = x;}
virtual T getval() { return val; }
};
template <class T>
class SqrNum : public Num<T> {
public:
SqrNum(T x) : Num<T>(x) {}
T getval() { return (val * val); }
};
int main(){
Num<int> *bp, numInt_ob(2);
SqrNum<int> *dp, sqrInt_ob(3);
Num<double> numDouble_ob(3.3);
bp = dynamic_cast<Num<int>*> (&sqrInt_ob);
if(bp) {
cout << "Cast from sqrNum<int>* to Num<int>* OK.\n"
<< "Value is " << bp->getval() << endl;
}
else
cout << "Error !\n\n";
dp = dynamic_cast<SqrNum<int>> (&numInt_ob);
if(dp)
cout << "Error !\n";
else {
cout << "Cast from Num<int>* to SqrNum<int>* not OK.\n"
<< "Can't cast a pointer to a base object into\n"
<< "a pointer to a derived object\n\n";
}
bp = dynamic_cast<Num<int>*> (&numDouble_ob);
if(bp)
cout << "Error" << endl;
else {
cout << "Can't cast from Num<double>* to Num<int>*.\n"
<< "These are 2 different types.\n\n";
}
return 0;
}
in the code above i m getting error that
Quote: error: 'val' was not declared in this scope
T getval() { return (val val); }
^~~
but
Quote: class SqrNum : public Num<t>
according to this the protected value in the base class should just work fine as protected value in the derived class, but it isn't ?
How do i solve this problem ?
EDIT :
below is the working code:
#include <iostream>
using namespace std;
template <class T>
class Num {
protected:
T val;
public:
Num(T x) { val = x;}
virtual T getval() { return val; }
};
template <class T>
class SqrNum : public Num<T> {
public:
SqrNum(T x) : Num<T>(x) {}
T getval() { return (Num<T>::val * Num<T>::val); }
};
int main(){
Num<int> *bp, numInt_ob(2);
SqrNum<int> *dp, sqrInt_ob(3);
Num<double> numDouble_ob(3.3);
bp = dynamic_cast<Num<int>*> (&sqrInt_ob);
if(bp) {
cout << "Cast from sqrNum<int>* to Num<int>* OK.\n"
<< "Value is " << bp->getval() << endl;
}
else
cout << "Error !\n\n";
dp = dynamic_cast<SqrNum<int>*> (&numInt_ob);
if(dp)
cout << "Error !\n";
else {
cout << "Cast from Num<int>* to SqrNum<int>* not OK.\n"
<< "Can't cast a pointer to a base object into\n"
<< "a pointer to a derived object\n\n";
}
bp = dynamic_cast<Num<int>*> (&numDouble_ob);
if(bp)
cout << "Error" << endl;
else {
cout << "Can't cast from Num<double>* to Num<int>*.\n"
<< "These are 2 different types.\n\n";
}
return 0;
}
Thank you
modified 6-Jun-18 0:49am.
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dp = dynamic_cast<SqrNum<int>*> (&numInt_ob);
Needs an '*' after <int>.
Code now runs successfully.
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i added * after SqrNum<int> but it is still giving that error .
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Did not give that error in the original code that I compiled.
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Quote: template <class t="">
class SqrNum : public Num<t> {
public:
SqrNum(T x) : Num<t>(x) {}
T getval() { return (val * val); }
};
Should be
template <class T>
class SqrNum : public Num<T> {
public:
SqrNum(T x) : Num<T>(x) {}
T getval() { return (Num<T>::val * Num<T>::val); }
};
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Quote: return (Num<t>::val * Num<t>::val);
but i have already inherited all the members of the base class to the derived class, then why i need to use scope resolution operator to point where to look for val ?
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How can i access the Device manager part of the Windows API?
I want to beable to show what certain devices are connected in a project in a custom application.
ill be Writing it in C++
Any ideas?
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This may be a good starting point.
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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Hi everyone!
I've been, for the past days, searching for the smallest executable for Windows. The reason is that I want to start a small macro for a game (basically just presses a key and maybe draw some pixels on screen), and I'd like it to be tiny, just for the sake of it. I'll not use NASM, however; I intend to use Ollydbg or another such tool to directly "code" in the executable itself (sort of like a challenge).
I searched the web for the smallest executable, and it appears to be 97 bytes large. I couldn't find it for download, but I don't think it would run in any version of Windows (I want it to run from XP up (XP,7,8,10)). I found one called "hh2 golden.exe" (~400 bytes), which apparently runs from XP up, but it prints "Hello World!" in the screen (I'd like one that did nothing).
Also, I couldn't assemble them (I don't know how to properly use NASM or other assembler). I'd use "hh2 golden.exe", but or other assemblerthen I had the idea to ask here if one of you guys have a better executable that I could use in this adventure.
tl;dr: I'm asking for the smallest executable capable of running from winXP up. Preferrably it does nothing, since I want to modify it and put some functionality to it (but I need it to be completely clear at the beginning)
Thanks!
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How can i be good on coding to start programming?
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Understand problem solving.
Ask questions.
Ability to think outside the box.
et al
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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You will work hardly.
You will learn hardly.
You will communicate with other programmers (in Forums, news groups, and so on) hardly.
...
Good luck!
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Quote: How can i be good on coding to start programming? I start programming in order to be good on coding.
FFY.
Experience matters.
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Programming is more than just writing code - it's about solving problems with code. You'll need to develop analysis and troubleshooting skills in addition to straight coding skills.
Having said that, the best way to learn how to write code is to actually write code. You could start by looking at Codecademy. It's free, it's all done in the browser (so you don't have to set up a development environment on your local machine), and they cover a useful range of languages.
I haven't used it much myself, so I can't comment on the quality of the instruction. It may be good, it may be awful. Depends on what you want to learn.
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Ability to follow instructions.
Ability to "read in-between lines" - not every programming task is spelled out in details.
There is a difference between being a "coder" which requires mastering the tool - programming language - of your choise, and being a programmer.
As already mentioned there is no substitute for experience.
Attention to details - loose the "don't sweat the small stuff attitude " fast.
And above all - start coding.
Best of luck
Cheers
Vaclav
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