How to combine hi and lo

[ascomm]

How do I combine high-byte and low-byte to one int?

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int range;
unsigned short highbyte, lowbyte;

highbyte = 1;
lowbyte = 234;

range = (highbyte << 8) | lowbyte;

As far as I know, this shoud do the trick but it doesn't...

[anton]

I think you must use ||

Code: Select all

int range;
unsigned short highbyte, lowbyte;

highbyte = 1;
lowbyte = 234;

range = (highbyte << 8) || lowbyte;

[rajkovic]

Code: Select all

int range;
unsigned short highbyte, lowbyte;

highbyte = 1;
lowbyte = 234;

range = (highbyte << 8) | lowbyte;

As far as I know, this shoud do the trick but it doesn't...

This works as a sample example:

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void main(){
int range;
unsigned short highbyte, lowbyte;

highbyte = 1;
lowbyte = 234;

range = (highbyte << 8) | lowbyte;
}

Please post the whole function in which it doesn't work.

New release of mikroC is planned by the end of this week (about 60 new funstions added ) . I believe we have fixed this and similar bugs. Please, post your code, just to be sure.

-

[ascomm]

Here is the whole function:

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int read_sonar_range(unsigned short SRF08ADDRESS)
{
  unsigned short highbyte, lowbyte;
  char *txt[7];
  int range;

  I2C_Start();                        // Generate start
  while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  I2C_Wr(SRF08ADDRESS);               // send sonar address
  while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  I2C_Wr(0x03);                       // send sonar register address
  while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  I2C_Repeated_Start();               // Generate repeated start
  //while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  I2C_Wr(SRF08ADDRESS+1);             // send address
  //while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  lowbyte = I2C_Rd(1);              // Read low-byte
  while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  highbyte = I2C_Rd(0);               // Read high-byte
  while (!I2C_Is_Idle()) asm nop;     // Wait until the I2C-bus is free
  I2C_Stop();                         // Generate stop
  Usart_Write(highbyte);
  Usart_Write(lowbyte);
  Lcd_Cmd(Lcd_CLEAR);
  ByteToStr(highbyte,txt);
  LCD_Out(1,1,"H:");
  LCD_Out(1,3,txt);
  ByteToStr(lowbyte,txt);
  LCD_Out(1,7,"L:");
  LCD_Out(1,9,txt);
  //highbyte = 1;
  //lowbyte = 25;
  range = (highbyte << 8) | lowbyte;
  IntToStr(range,txt);
  LCD_Out(2,1,"H+L:");
  LCD_Out(2,5,txt);
  return (0);
}

I don't know what was going on before, but now this byte combining works just as it should.
So, no panic

[gambrose]

would be nice to get access to each byte in ints and longs in the same sort of way we can access individual bits.

have you considered using a pointer to byte assigning it the value of range then loading in highbyte adding one (or subtracting one i can't remember which) to the pointer then assigning lowerbyte.
i think this method should be quicker than shifting highbyte left 8 times.

if you could also explore two constant pointers. i don't know how mikroC handles constant pointers but i know that it handles constants fairly well so you might get away with having the speed but with out using up any more memory.

[ascomm]

have you considered using a pointer to byte assigning it the value of range then loading in highbyte adding one (or subtracting one i can't remember which) to the pointer then assigning lowerbyte.

I'm not so familiar with pointers, so no I have not considered them.
Maybe someone could give an example how to use pointers in this case??

[gambrose]

Code: Select all

int range; // declare you int
unsigned short * ptr = ⦥ // obtain a reference to it

* ptr = 234; // load lower byte first
ptr++; // increment the pointer
* ptr = 1; // load the higher byte

note: Numbers are stored lowest byte first.

[pizon]

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int range; // declare you int
unsigned short * ptr = ⦥ // obtain a reference to it

* ptr = 234; // load lower byte first
ptr++; // increment the pointer
* ptr = 1; // load the higher byte

Yes, this is a standard C way of doing such things. mikroC has a useful extension to handle such cases, which is 'stolen' from mikroPascal, and these are the built-in functions for byte access at multi-byte variables: Lo(), Hi(), Higher() and Highest(). As you see, they cover variables of up to 4 bytes, and can be used for all the fundamental data types (except for the floating point). You can access structure elements as well, but it doesn't pay off since access to structure members is direct anyway.

[gambrose]

that is very interesting.
these functions are not documented in the current mikroC are they due for the next release?

could you give a brief example on how to use them?

[LGR]

could you give a brief example on how to use them?

Just download the Pascal manual (or, I think, Basic).

[pizon]

these functions are not documented in the current mikroC are they due for the next release?

They are already implemented, and we'll document them in the next Help release. In the meantime, you can see how they work from mikroBasic or mikroPascal's Help. In short:

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long sl1;
unsigned short us;
...
us = Lo(sl1);     // us <- sl1_1
us = Hi(sl1);     // us <- sl1_2
us = Higher(sl1);     // us <- sl1_3
us = Highest(sl1);     // us <- sl1_4

[gambrose]

I had a little play with these functions and looked at the help files in mikroPascal.
I think the functions are very good as they are proper built in functions that insert the correct assembler name not a function call.

i feel that the way they are documented in the help file is a little misleading as they are described using a function prototype.

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function Hi(number : word..longint) : byte;

this applies that a function call will be made which is untrue and it also leads you to believe that you can not assign to the Hi byte of a number which is also untrue (i checked).
I realise that you wish to keep a uniform feel to the help files but a note that this is not actually a function call and a example of assigning to the byte as well would make a more complete help file.