Hi all,

I'm working on my first port from Sinclair Basic to ZX Basic. I'm excited about it. I'd love to program compiled versions of some old programs of mine, but first I need to acquaint with this wonderful and impressive tool.

I'm using ZX Basic 1.2.0 under Debian GNU/Linux.

Well, I think I found a kind of bug. Here you are the test:

Okay. This release is already available for download, and fixes a -O3 bug (another one). The most common effect is some optimizations NOT being done.
Please, download and test: <!-- m --><a class="postlink" href="http://www.boriel.com/files/zxb/zxbasic-1.2.6r1542.msi">http://www.boriel.com/files/zxb/zxbasic-1.2.6r1542.msi</a><!-- m -->

This issues a warning: "Test.bas:22: warning: Redundant operation ABS for unsigned value"

Surely if a Byte is signed, then (Byte-Byte) is signed as well?

Is this an internal issue, or is it me doing something wrong, and I should be casting, here?

(I know poking the routine with fspDataStart is a bad idea - I needed label to be able to make this compile on its own to demonstrate the query - I'm not really writing horrifically wrong self-modifying code!)

Ok, this release is just 1.2.5-r1513h renamed. I think it's quite stable now, and if new bugs are found, they will be fixed on 1.2.6.
So, those interested, please, download from: <!-- m --><a class="postlink" href="http://www.boriel.com/files/zxb">http://www.boriel.com/files/zxb</a><!-- m -->

Thanks to Britlion, apenao, LCD & carloscomputer. They've detected more than 30 bugs. In fact this version fixes so many that some parts has been completely rewritten. If you use any older version, do please upgrade to this one immediately. This version could be considered as a "Service Pack Update".

Changes since v.1.2.4
===================================

• Assembler:
  • ! Under some pathological cases, compiling or assembling will last for exponential time (minutes to hours!), due to a possible bug/misuse of a regular expression. Fixed. Now it takes linear time.
    
  • + Added support for IXh, IXl, IYh, IYl registers.
    
  • + Added support for DEFS macro. Now DEFS n, B creates a block of n times byte B
    
  • ! Instructions LD A, R and LD R, A where also missing. Fixed.
• Compiler
  • ! The optimizer -O2 was broken, and contained 3 bugs. Fixed.
    
  • ! The optimizer -O3 was broken, and contained more than 15 bugs. It's been almost completely rewritten. Fixed. Now it even tries to optimize ASM users code. :!:
    
  • ! The @operator was broken under some circumstances (array accesses and variables). Fixed.
    
  • ! The memory heap was also broken almost always when using any string in the program (INKEY$, STR$, CHR$, $ variables). Fixed.
    
  • ! Signed LONG division was wrong for positive divisors. Fixed.
    
  • ! Byte comparison operators < > = >= <= were sometimes bugged. Fixed.
    
  • ! using MOD with Fixed type was unsupported. Fixed. Now MOD used Fixed type.
    
  • ! INT(Fixed) was wrong. Fixed.
    
  • ! Temporary attributes BOLD and ITALIC were disabled. Now they are back.
  
  Probably some more other fixed, but these are the most important. :wink:

There *is* in fact a line number bug. It's in the inline assembly.

I noticed that the assembler doesn't like using IX and IY as half registers. Is it unsupported, or using a different syntax than the one I expected - LD IXH,A ?

Technically, they aren't official Zilog instructions, but most assemblers go for them. It's sometimes really handy to load IX and IY in halves, or you desperately need that extra register :-)

From a manual on assembler:


More Control Over Index Registers
You know, you can access the high and low bytes of IX and IY. It's a little more complicated because the instructions aren't officially supported by ZiLog, and it is a little on the unelegant side. Nevertheless they can be useful in some circumstances, like when all your registers are locked up and you need an 8-bit counter bad.
The high byte of IX is called either IXH or HX (remember these are unofficial registers so there are no standard names). The low byte is called either IXL or LX. The high and low bytes of IY are named similarly.

To use a part of an index register in an instruction:

Pick an instruction that allows both H and L to be used as an operand, excepting shifts, rotates, BIT, SET, and RES.
Use H if you want the high byte, or L if you want the low byte.
Immediately precede this instruction with .DB $DD to use the IX half-registers, or .DB $FD to use the IY half-registers.
Example: LD E, IXH
.DB $DD
LD E, H

Example: SUB IYL
.DB $FD
SUB L

Be aware that once you specify a prefix, you are locked into using that index register's half-registers. It is impossible to combine the half-registers of HL, IX, or IY in one instruction:
.DB $DD ;LD IXH, IXL
LD H, L

Tip of the day:

Clearly, a US keyboard doesn't have this £ thing. I have no idea if it's on a spanish or austrian one. I doubt it. So, just in case you need it, with a default US character set, the ` (back quote) seems to do the same job in compiled code.

Chances are I'm the only person that's relevant to. But hey I'm sharing anyway. Hush.

I have polished a bit my sprite routine, writting it in just one file and erasing repeated code (it worked OK up to this point) and adding a new subroutine to set the background colour of the playing area. Wheter I use or not this routine (and even if I take it out of the sprite routine file and copy it in any part of the main program code) its causing the graphics behave strangely.

When I'm drawing the "show room" (the only one atm, where I'm trying the graphics and the movements) I call (via Gosub) the routines drawing the different parts, i.e.:
GOSUB ESQUINA -- DRAWS THE CORNERS
GOSUB HABITACINESCONPUERTA -- DRAWS THE "WALLS" AND THE DOORS

When I draw the decoration parts (i.e. a carpet, or different floor designs) I see one of the coordinates of the sprites is changed:

If I draw the carpet (GOSUB ALFOMBRA), then the transparent window has its Y coordinate changed, whatever the correct value is.

If I draw the star (GOSUB ESTRELLA), the main sprite's X coordinate is changed.

And so on. I'll copy the .bas files for the game and the library so you can check it changing between the decorations (MADERA, FLECHAIZDA,FLECHADERECHA,ESTRELLA,SUELOEQUIS,LABERINTO). Perhaps it makes any sense to you. I don't include the .rle file because its the same I sent you last time.



The main program:

This version enhances zxbasm (ZX BASIC assembler), so the compilation process is much much faster:
Download here: <!-- m --><a class="postlink" href="http://www.boriel.com/files/zxb/zxbasic-1.2.5r1513e.msi">http://www.boriel.com/files/zxb/zxbasic-1.2.5r1513e.msi</a><!-- m -->