#2946 sdasstm8 bugs

[Picatout]

the sdasstm8 assembler code is in error for the following 2 instructions:
div x,y code 0x62 instead of 0x65
jrxx . (conditonnal jump to istself) give a relative address short of 1 byte. It jump after the 0x90 prefix. It is ok for no prefix jrxx instructions.

[Philipp Klaus Krause]

I just tested a small sample program using current SDCC. div x, y is assembled to 0x62, just as the STM8 CPU programming manual says it should.

[Picatout]

DIV X,Y is not a valid instruction and should trigger an error message. The valid instruction is DIVW X,Y with opcode 0x65. opcode 0x62 is for DIV X,A

[Philipp Klaus Krause]

Regarding jrh, etc: These actually seem wrong according to the STM8 CPU programming manual. However, before changing it in the assembler, I'd like to see this verified on real hardware (the 2-byte jrxx instructions add the 2 to the pc before addign the offset, so what about these 0x90-prefixed 3-byte jrxx? Do they also add 2, like the manual says, or 3, like the assembler assumes??

[Eric Rullens]

Using the assembler in the STVP tool, it looks like the 0x90-prefixed opcodes add 3.

0x8000 | 0x2706 | JREQ 0x8008

So 0x8000 + 2 + 6 = 0x8008.

0x8010 | 0x902905 | JRH 0x8018

So 0x8010 + 3 + 5 = 0x8018.

And an example for a conditional "jump to self":

0x8020 | 0x9029FD | JRH 0x8020

So 0x8020 + 3 - 3 = 0x8020.

The PM0044 Rev 2 manual says on JRxx:

Syntax:
JRxx dst

Operation:
PC = PC+lgth
PC <= PC + dst, if Condition is True

In the instruction list lgth is listed as 2 or 3 depending on the 0x90 prefix.

Funnily enough, for the JRH instruction used in the example above, the manual shows a 0x29 opcode in the overview list. But 0x29 is the JRV instruction in the same list. The specific table in the JRxx section lists JRH correctly as 0x90 0x29.

[Picatout]

ASxxxx Assembler V02.00 + NoICE + SDCC mods  (STMicroelectronics STM8), page 2.
Hexadecimal [24-Bits]



                                     56         ;ld a, #0x80
                                     57         ;ld WWDG_CR,a ; WWDG_CR used to reset mcu
                                     58     ;iret
                                     59 
                           0017FF    60 STACK=0x17ff 
      000001                         61 main:
                                     62 ; initialize SP
      000001 AE 17 FF         [ 2]   63         LDW     X,#STACK  ;initialize return stack
      000004 94               [ 1]   64         LDW     SP,X
      000005 90 29 FE         [ 1]   65         JRH     .
      000008 20 FE            [ 2]   66         JRA     . 

For the instruction JRH . it should be 90 29 FD as it is it jump to 29 which is JRV