FvM
Joined: 27 Aug 2008
Posts: 2337
Location: Germany
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| PCD V4.127 not preserving registers in printf("%x" |
 Posted: Sun Nov 27, 2011 3:05 pm |
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Hello,
I'm still struggling to find a stable PCD version newer than V4.112. Just when I thought, V4.127 could be a candidate,
I stumbled upon a new bug, that wasn't yet present in V4.125. (Unfortunately, the latter has other and more bugs,
so falling back to V4.125 isn't a good option...).
I could implement a workaround in the present case, but not preserving registers in internal function calls is a
serious issue, thus I wonder if the same problem shows in other places as well.
| Code: | #include <24F16KA102.h>
#device icd=2
#FUSES HS //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#use delay(clock=20000000)
#use RS232(baud=19200, UART1)
#define W4_BUGFIX 0
void _putc(unsigned int8 c)
{
int16 l;
#IF getenv("VERSION")==4.127 && W4_BUGFIX
#asm MOV W4,[W15++] #endasm
#ENDIF
l=l*3;
putc(c);
#IF getenv("VERSION")==4.127 && W4_BUGFIX
#asm MOV [--W15],W4 #endasm
#ENDIF
}
void main()
{
unsigned int16 us;
us=9;
printf(_putc,"printf_x fails in V4.127 because W4 isn't preserved V%3x\r\n",us);
while (1);
} |
Generated printf output:
"printf_x fails in V4.127 because W4 isn't preserved
V009000000000000000000000000000000000
00000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000"
And that's how the erroneous printout is brought up. @PRINTF_X_74 is the internal print function called with
%x format for a 16 bit integer.
| Code: | @PRINTF_X_74:
0256: MOV W0,W3
0258: SWAP W1
025A: MOV.B #5,W4L ; W4 used as digit counter
025C: DEC.B 0003
025E: DEC.B 0008 ; W4L--
0260: BRA Z,290
0262: MOV W3,W0
0264: SL W3,#4,W3
0266: LSR W0,#C,W0
0268: AND #F,W0
026A: BRA NZ,274
026C: CP.B W4L,#1
026E: BRA Z,274
0270: BTSS.B 3.7
0272: BRA 25C
0274: ADD #30,W0
0276: MOV #3A,W2
0278: CP W0,W2
027A: BRA NC,27E
027C: ADD.B 2,W0L
027E: MOV W1,[W15++]
0280: MOV W3,[W15++]
0282: MOV.B W0L,85F
0284: CALL 244 ; W4 not preserved
0288: MOV [--W15],W3
028A: MOV [--W15],W1
028C: BSET.B 3.7
028E: BRA 25C
0290: RETURN
.................... void _putc(unsigned int8 c)
.................... {
.................... int16 l;
.................... l=l*3;
*
0244: MOV 860,W4 ; W4 is overwritten
0246: MUL.UU W4,#3,W0
0248: MOV W0,860
.................... putc(c);
024A: MOV.B 85F,W0L
024C: BTSC.B 223.1
024E: BRA 24C
0250: MOV.B W0L,224
0252: CLR.B 225
.................... }
0254: RETURN |
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