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hayee
Joined: 05 Sep 2007
Posts: 252
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| wanna write code in assembly language in CCS compiler |
 Posted: Tue May 28, 2013 6:51 am |
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Hi
i never write an assembly code in CCS compiler. Now i want to write assembly in ccs compiler and want to use the following code in it
| Code: |
NUME EQU 0x15
QU EQU 0x20
RMND_L EQU 0X22
RMND_M EQU 0X23
RMND_H EQU 0X24
MYNUM EQU 0XFD
MYDEN EQU D'10'
ORG 0H
MOVLW MYNUM
MOVWF NUME
MOVLW MYDEN
CLRF QU,F
D_1 INCF QU,F
SUBWF NUME
BC D_1
ADDWF NUME
DECF QU,F
MOVFF NUME,RMND_L
MOVFF QU,NUME
CLRF QU
D_2 INCF QU,F
SUBWF NUME
BC D_2
ADDWF NUME
DECF QU,F
MOVFF NUME,RMND_M
MOVFF QU,RMND_H
HERE GOTO HERE
END
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can anyone tell me, Is CCS allow us to write code in assembly? if yes then whats the syntax for that.
Give me a very simple example guys.
Thanks |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue May 28, 2013 7:18 am |
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There is nothing there that couldn't be done easier in C....
For instance:
| Code: |
#define NYNUM 0xFD
#byte NUME=0x15
NUME=NYNUM;
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Does what the first two assembler lines do....
However, look at EX_FIR.C, and EX_GLINT.C, for examples of embedding assembler in the C code (and look at #ASM in the manual).
A few years ago, it was common to have to use assembler, but the abilities of some of the commands like #byte, have basically made it unnecessary now.
Best Wishes |
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temtronic
Joined: 01 Jul 2010
Posts: 9225
Location: Greensville,Ontario
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| Posted: Tue May 28, 2013 11:59 am |
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after staring at the code it appears to take a value from 0 to 255 and'break it up' into hundred,tens and ones digits.
ie: give 123 and you'll get back 1,2 and 3 in some variables.
If so there is code here in this forum(you'll have to search for it).
Depending on how the C code is written and compiled it may not be any faster or compact that the assembler
It'll be up to you which to use.
hth
jay |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Tue May 28, 2013 2:38 pm |
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You are welcome to learn assembly language but unless there is a strong reason for performance optimization I would strongly discourage using it. Assembly language is much harder to follow and so debugging and maintaining your program will become more difficult.
The CCS compiler is a C compiler. It can do assembly but because of where it comes from some details are different than in the other compilers you are copying the assembly code from.
For example, in CCS the variables are automatically assigned to free RAM addresses. In other compilers you as a programmer have to do this which is more difficult and also has the disadvantage that the compiler can not do memory optimization by re-using the RAM for multiple variables when possible.
Here is your program converted to C: | Code: | #include <18F458.h>
#FUSES HS, NOWDT, PUT, NOLVP
#use delay(clock=4MHz)
#byte STATUS = getenv("SFR:STATUS")
#bit CARRY_BIT = STATUS.0
int8 NUME;
int8 QU;
int8 RMND_L;
int8 RMND_M;
int8 RMND_H;
#define MYNUM 0XFD
#define MYDEN 10
void main()
{
// Calculate Least significant digit
NUME = MYDEN;
QU = 0;
do {
QU++;
NUME -= MYDEN;
} while (CARRY_BIT);
// correct after overflow
NUME += MYDEN;
QU--;
RMND_L = NUME;
// Calculate Second digit
NUME = QU;
QU = 0;
do {
QU++;
NUME -= MYDEN;
} while (CARRY_BIT);
// correct after overflow
NUME += MYDEN;
QU--;
RMND_M = NUME;
// Store remainder as Most significant digit
RMND_H = QU;
while(1);
} |
And the list file to show it is almost the same: | Code: | .................... // Calculate Least significant digit
.................... NUME = MYDEN;
0014: MOVLW 0A
0016: MOVWF NUME
.................... QU = 0;
0018: CLRF QU
.................... do {
.................... QU++;
001A: INCF QU,F
.................... NUME -= MYDEN;
001C: MOVLW 0A
001E: SUBWF NUME,F
.................... } while (CARRY_BIT);
0020: BC 001A
....................
.................... // correct after overflow
.................... NUME += MYDEN;
0022: MOVLW 0A
0024: ADDWF NUME,F
.................... QU--;
0026: DECF QU,F
....................
.................... RMND_L = NUME;
0028: MOVFF NUME,RMND_L
....................
.................... // Calculate Second digit
.................... NUME = QU;
002C: MOVFF QU,NUME
.................... QU = 0;
0030: CLRF QU
.................... do {
.................... QU++;
0032: INCF QU,F
.................... NUME -= MYDEN;
0034: MOVLW 0A
0036: SUBWF NUME,F
.................... } while (CARRY_BIT);
0038: BC 0032
....................
.................... // correct after overflow
.................... NUME += MYDEN;
003A: MOVLW 0A
003C: ADDWF NUME,F
.................... QU--;
003E: DECF QU,F
....................
.................... RMND_M = NUME;
0040: MOVFF NUME,RMND_M
....................
.................... // Store remainder as Most significant digit
.................... RMND_H = QU;
0044: MOVFF QU,RMND_H
....................
.................... while(1);
0048: BRA 0048 |
The pure assembly version is a tiny bit faster because the W-register is only loaded once and outside the loop. The C-version loads the W-register two times and does it the first time inside the first loop. However, that tiny bit performance gain doesn't weight against the better maintainability.
Personally, I prefer the version from the Code Library: http://www.ccsinfo.com/forum/viewtopic.php?t=27600 | Code: | void GetDigits(int16 val, int8 &hundreds, int8 &tens, int8 &units)
{
tens = 0;
hundreds = 0;
while (val >= 100)
{
val -= 100;
hundreds++;
}
while (val >= 10)
{
val -= 10;
tens++;
}
units = val;
}
//===============================
void main ()
{
int16 adcvalue;
int8 hundreds,tens,units;
adcvalue = 115;
GetDigits(adcValue, hundreds, tens, units);
while (1);
} |
Same code size as the assembly version but way easier to understand and less lines to read as well. |
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oxo
Joined: 13 Nov 2012
Posts: 219
Location: France
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| Posted: Thu May 30, 2013 2:48 am |
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You win the thread ckielstra.
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