Hi all,
I encounter a strange behaviour with the pic14 target of sdcc. I'm
posting this here first instead of reporting a bug because I'm not very
experienced with sdcc yet and I want to make sure that it's not actually
my own fault.
The problem is that a simple piece of code produces wrong assembler
code. I have a little LCD control function such as
static void display_data(unsigned char c)
{
//PORTA = 0xaa;
if(cmd_or_data)
{
PORTA |= 2;
}
else
{
PORTA &= ~2;
}
PORTB = c; PENABLE;
c <<= 4;
PORTB = c; PENABLE;
cmd_or_data = DATA;
}
which produces the assembler output
;***
; pBlock Stats: dbName = C
;***
;entry: _display_data ;Function start
; 2 exit points
;has an exit
;1 compiler assigned register :
; r0x27
;; Starting pCode block
_display_data ;Function start
; 2 exit points
; .line 131; "main.c" static void display_data(unsigned char c)
BANKSEL r0x27
MOVWF r0x27
;; peep 7 - Removed redundant move
; .line 134; "main.c" if(cmd_or_data)
MOVF _cmd_or_data,W
BTFSC STATUS,2
GOTO _00150_DS_
; .line 136; "main.c" PORTA |= 2;
BCF STATUS,5
BCF STATUS,6
BSF _PORTB,1 ; <---- ????
GOTO _00151_DS_
_00150_DS_
; .line 140; "main.c" PORTA &= ~2;
BCF STATUS,5
BCF STATUS,6
BCF _PORTB,1 <---- ????
_00151_DS_
(snip)
So I believe the compiler confuses PORTA and PORTB here. However, when
the commented first line of the function body is uncommented, the output
is correct:
;***
; pBlock Stats: dbName = C
;***
;entry: _display_data ;Function start
; 2 exit points
;has an exit
;1 compiler assigned register :
; r0x27
;; Starting pCode block
_display_data ;Function start
; 2 exit points
; .line 131; "main.c" static void display_data(unsigned char c)
BANKSEL r0x27
MOVWF r0x27
; .line 133; "main.c" PORTA = 0xaa;
MOVLW 0xaa
BCF STATUS,5
BCF STATUS,6
MOVWF _PORTA
;; peep 7 - Removed redundant move
; .line 134; "main.c" if(cmd_or_data)
BANKSEL _cmd_or_data
MOVF _cmd_or_data,W
BTFSC STATUS,2
GOTO _00150_DS_
; .line 136; "main.c" PORTA |= 2;
BCF STATUS,5
BCF STATUS,6
BSF _PORTA,1 <--------- !!
GOTO _00151_DS_
_00150_DS_
; .line 140; "main.c" PORTA &= ~2;
BCF STATUS,5
BCF STATUS,6
BCF _PORTA,1 <--------- !!
The compilation command is sdcc -mpic14 --no-pcode-opt -p16f628 main.c
I used the 2.6.0 version of the compiler on Linux, built from the
sources. Please let me know if any other info is missing.
Best regards,
Dietmar
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