What's New in C51 Version 9.59

[New Supported Devices]
- Silabs
  EFM8UB30F40G_QFN20, EFM8UB31F40G_QFN24, EFM8UB31F40G_QSOP24,
- Weltrend
  WT51F116, WT51F108, and WT51F104.
[AX51 Macro Assembler]
- Corrected: allow slash '/' in addition to backslash '\' as a directory separator in all places

Corrected: sometimes the compiler shows warning C290: missing return value or warning C291: not every path returns a value although a value is returned.

Corrected: in some cases post increment was not applied. Example:

unsigned char reader;
unsigned char count;
unsigned int  index;

index = 0;

write_byte(offset);

for (count = 0; count < 10; count++) {
  reader = read_byte();
  pData[index++] = reader;
}
...

Wrong code was generated:

...
000D 120000      R     LCALL   read_byte
;---- Variable 'reader' assigned to Register 'R5' ----
0010 AD07              MOV     R5,AR7
0012 EB                MOV     A,R3
0013 2500        R     ADD     A,index+01H
0015 F582              MOV     DPL,A
0017 EA                MOV     A,R2
0018 3500        R     ADDC    A,index
001A F583              MOV     DPH,A
001C ED                MOV     A,R5
001D F0                MOVX    @DPTR,A
001E 0C                INC     R4
...

now the correct code is generated:

...
;---- Variable 'reader' assigned to Register 'R5' ----
001A AD07              MOV     R5,AR7
001C 8B82              MOV     DPL,R3
001E 8A83              MOV     DPH,R2
0020 0500        R     INC     index+01H
0022 E500        R     MOV     A,index+01H
0024 AE00        R     MOV     R6,index
0026 7002              JNZ     ?C0007
0028 0500        R     INC     index
002A         ?C0007:
002A 14                DEC     A
002B 2582              ADD     A,DPL
002D F582              MOV     DPL,A
002F E583              MOV     A,DPH
0031 3E                ADDC    A,R6
0032 F583              MOV     DPH,A
0034 ED                MOV     A,R5
0035 F0                MOVX    @DPTR,A
0036 0C                INC     R4
...

Corrected: allow slash '/' in addition to backslash '\' as a directory separator in all places

Corrected: in rare cases a signed compare with unsigned char treated the unsigned char as signed. This happens if the unsigned char value results from a calculated assignment. Example:

char i;
unsigned char uc0 = 254;
char c1 = 0;

void main() {
  if (c1 <= (uc0 += c1))    // uc0 is wrongly treated signed => -2 therefore the condition (0 <= -2) is false
    i = 1;
  else
    i = 0;
}

Wrong code was generated:

0000 E500        R     MOV     A,uc0
0002 2500        R     ADD     A,c1
0004 F500        R     MOV     uc0,A
0006 D3                SETB    C
0007 6480              XRL     A,#080H       \ 
0009 F8                MOV     R0,A          |
000A E500        R     MOV     A,c1          |
000C 6480              XRL     A,#080H       |
000E 98                SUBB    A,R0          |
000F 5004              JNC     ?C0001        -> signed char compare
0011 750001      R     MOV     i,#01H
0014 22                RET
0015         ?C0001:
0015 E4                CLR     A
0016 F500        R     MOV     i,A
0018         ?C0003:
0018 22                RET

The correct code is much longer because according to the C standard a cast to int is necessary:

0000 E500        R     MOV     A,uc0
0002 2500        R     ADD     A,c1
0004 FF                MOV     R7,A
0005 F500        R     MOV     uc0,A
0007 AD00        R     MOV     R5,c1         \ 
0009 ED                MOV     A,R5          |
000A 33                RLC     A             |
000B 95E0              SUBB    A,ACC         |
000D FC                MOV     R4,A          -> cast of signed char to int
000E D3                SETB    C             \ 
000F ED                MOV     A,R5          |
0010 9F                SUBB    A,R7          |
0011 7480              MOV     A,#080H       +> implicit cast of unsigned char to int
0013 F8                MOV     R0,A          |
0014 6C                XRL     A,R4          |
0015 98                SUBB    A,R0          |
0016 5004              JNC     ?C0001        -> signed int compare
0018 750001      R     MOV     i,#01H
001B 22                RET
001C         ?C0001:
001C E4                CLR     A
001D F500        R     MOV     i,A
001F         ?C0003:
001F 22                RET

To generate smaller code the signedness of the values to be compared should be the same:

...
    if ((unsigned char)c1 <= (uc0 += c1))
...
0000 E500        R     MOV     A,uc0
0002 2500        R     ADD     A,c1
0004 FF                MOV     R7,A
0005 F500        R     MOV     uc0,A
0007 E500        R     MOV     A,c1
0009 D3                SETB    C             \ 
000A 9F                SUBB    A,R7          |
000B 5004              JNC     ?C0001        -> unsigned char compare
000D 750001      R     MOV     i,#01H
0010 22                RET
0011         ?C0001:
0011 E4                CLR     A
0012 F500        R     MOV     i,A
0014         ?C0003:
0014 22                RET

[LX51 Linker/Locater]
- Corrected: in rare cases the linker crashes if using long function names and Global Register Coloring
- Corrected: somehow not only function names were listed in the call tree and warning L48: IGNORED RECURSION, CALL REMOVED appeared
- Corrected: sometimes automatic rebuilds are not executed when Global Register Coloring is used
- Corrected: in case of banked applications and under some circumstances the CONST- as well as the CODE-Segments located to the same bank address.
- Corrected: under some circumstances the MERGEPUBLICS does not work for sbit variables.
[Debug Commands]
- Added: New debugger command COVTOFILE filespec [\\app][\module][\function] [DETAILS] [ASM] which works like the COVERAGE command but sends the output into a file. This is much faster than into the output window.
[µVision]
- This C51 release comes with µVision V5.25.3.
[Supported Operating Systems]
- Refer to System Requirements Overview for hardware and operating system requirements.

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