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red_one
Joined: 30 Nov 2007
Posts: 10
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| shift_left/right use |
 Posted: Mon Dec 17, 2007 3:22 am |
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Hello All;
If I want to shift 32-bits integer left or right by one bit what to put as byte count ?
| Code: | | bit_out = shift_left(number32, ??, bit_in); |
Thanks |
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meereck
Joined: 09 Nov 2006
Posts: 173
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| Posted: Mon Dec 17, 2007 4:07 am |
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see the compiler reference manual : http://ccsinfo.com/downloads/CReferenceManual.pdf
| Quote: | shift_left (address, bytes, value)
address is a pointer to memory, bytes is a count of the number of bytes to work with, value is a 0 to 1 to be shifted in. |
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red_one
Joined: 30 Nov 2007
Posts: 10
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| Posted: Mon Dec 17, 2007 4:18 am |
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| meereck wrote: | see the compiler reference manual : http://ccsinfo.com/downloads/CReferenceManual.pdf
| Quote: | shift_left (address, bytes, value)
address is a pointer to memory, bytes is a count of the number of bytes to work with, value is a 0 to 1 to be shifted in. |
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so what "count of the number of bytes to work with" does mean ?
32-bits = 4 bytes, should I take 4 as a count ? |
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Ken Johnson
Joined: 23 Mar 2006
Posts: 197
Location: Lewisburg, WV
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| Posted: Mon Dec 17, 2007 7:57 am |
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| Quote: |
If I want to shift 32-bits integer left or right by one bit what to put as byte count ?
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Sounds like you want this:
| Code: |
int32 x;
x <<= 1; // Shifts left 1 bit
x >>= 1; // Shifts right 1 bit
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Ken |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Mon Dec 17, 2007 9:30 am |
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Yes!
4 is the count
int32,... 32bits... 8bits/byte ..... 32bits/8=4 |
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aopg64
Joined: 17 Oct 2005
Posts: 28
Location: Hampshire, UK
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| Another shift_left/shift_right problem |
| Posted: Wed May 28, 2008 4:50 am |
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Hi folks,
I'm trying to use common code to do reads and writes to a Microchip 25AA256 EEPROM from an 18F4620 using CCS V3.249.
I use a common command buffer (cmd[4]) and pass in a variable number (1 to 4) for the number of bytes in the command.
Unfortunately the shift functions only seem to allow a fixed number-of-bytes value.
I've tried size_t casting and so on.
Here's the code fragment:
| Code: | void ExtEEPROM_SendCmd(uint8 NumBytes)
{
uint8 i;
ExtEEPROM_Select();
for(i=0; i< (NumBytes*8) ; i++)
{
BB_ExternalEEPROM_PIC_SDO = shift_left(cmd,NumBytes,0);
ExtEEPROM_LatchBit();
}
}
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It's the variable 'NumBytes' in the shift_left that the compiler objects to.
The CCS help file doesn't specify what data type this value should be. I've tried 16-bit casts too.Maybe it should be const'ed?
Anybody got any ideas? Or will I just have to code each command sequence individually?
TIA,
Nige
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