[sdcc-devel] [ sdcc-Feature Requests-863474 ] i = ((int)c1<<8) | c2; is rather long

[SourceForge.net <no...@so...>]

Feature Requests item #863474, was opened at 2003-12-20 12:54
Message generated for change (Comment added) made by bernhardheld
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=350599&aid=863474&group_id=599

Category: None
Group: None
Status: Open
Priority: 5
Submitted By: Frieder Ferlemann (frief)
Assigned to: Nobody/Anonymous (nobody)
Summary: i = ((int)c1<<8) | c2; is rather long

Initial Comment:
the relatively common operation of combining 
two unsigned char variables into an integer  
produces long code: 
 
unsigned char c1,c2; 
unsigned int i; 
 
void main() 
{ 
  i = ((int)c1<<8) | c2; 
} 
 
;test.c:7: i=((int)c1<<8) | c2; 
;     genCast 
        mov     r2,_c1 
        mov     r3,#0x00 
;     genLeftShift 
;     genLeftShiftLiteral 
;     genlshTwo 
        mov     ar3,r2 
        mov     r2,#0x00 
;     genCast 
        mov     r4,_c2 
        mov     r5,#0x00 
;     genOr 
        mov     a,r4 
        orl     a,r2 
        mov     _i,a 
        mov     a,r5 
        orl     a,r3 
        mov     (_i + 1),a 
 
(likewise if you use '+' instead of '|') 
 
Frieder 

----------------------------------------------------------------------

>Comment By: Bernhard Held (bernhardheld)
Date: 2003-12-20 13:36

Message:
Logged In: YES 
user_id=203539

Still not perfect, but much shorter: 
 
void foo() 
{ 
  ((char near *) &i)[0] = c2; 
  ((char near *) &i)[1] = c1; 
} 

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=350599&aid=863474&group_id=599