mandelbrot drawing CPU benchmark

[danboid]

Youtube channel The Retro Desk created a mandelbrot drawing program that they have used to benchmark the CPU performance of various (modern) retro computer platforms. You can download the code for this benchmark for various platforms here:

https://github.com/SlithyMatt/multi-mandlebrot

Z80N assembler code is present in that repo but I do not know (Z80) assembler so I have been unable to get it to build and they haven't uploaded any binaries for the Next. I'd like to know how the Z80N running at full speed (28 Mhz) compares to the Agon Light 2 and the Uzebox. I already know the Uzebox is the fastest but by how much, compared to the Next?

I have looked at some other bits of asm for the Next and it seems that if I want to build this with sjasmplus then I need to do at least two things, I think:

Add some statements like these to the top of the file:

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; Allow Next paging and instructions
	DEVICE ZXSPECTRUMNEXT
	SLDOPT COMMENT WPMEM, LOGPOINT, ASSERTION

Then the hard part is getting the SAVENEX statements right which it seems need to go at the end of the .asm file. I tried the following which didn't work because I copy/pasted it without really understanding wtf I am doing, as I freely admit:

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;;--------------------------------------------------------------------
;; Set up .nex output
;;--------------------------------------------------------------------

	; This sets the name of the project, the start address,
	; and the initial stack pointer.
	SAVENEX OPEN "mand24.nex", 0, $ff40

	; This asserts the minimum core version.  Set it to the core version
	; you are developing on.
	SAVENEX CORE 2, 0, 0

	; This sets the border colour while loading (in this case white),
	; what to do with the file handle of the nex file when starting (0 =
	; close file handle as we're not going to access the project.nex
	; file after starting.  See sjasmplus documentation), whether
	; we preserve the next registers (0 = no, we set to default), and
	; whether we require the full 2MB expansion (0 = no we don't).
	SAVENEX CFG 7, 0, 0, 0

	; Generate the Nex file automatically based on which pages you use.
	SAVENEX AUTO

This doesn't work. I get some nonsense error when I run it instead of a fractal being drawn. I've read the sjasmplus docs for SAVENEX and I was absolutely none the wiser and I am out of my depth here. It goes without saying you can't fix code you don't understand.

Could someone who does know z80 for the Next please take pity and tell me how I get these programs building and running? I can then submit a PR for the repo if you don't want to do that, although it looks like its a dead project.

Any recommended tutorials for assembly coding on the Next?

[flatduckrecords]

It looks like the asm files in the ZXN directory already have the correct SjASMPlus directives, so I was able to assemble just by running the build.sh file, but you could also invoke it directly:

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sjasmplus --lst zxn-mandelbrot.asm
sjasmplus --lst zxn-mandelbrot2.asm
sjasmplus --lst zxn-mandelbrot_127_63_15.asm
sjasmplus --lst zxn-mandelbrot_max_lores.asm
sjasmplus --lst zxn-mandelbrot_max_layer2.asm

If that doesn't work I can share the assembled .nex files.

[Einar Saukas]

Youtube channel The Retro Desk created a mandelbrot drawing program that they have used to benchmark the CPU performance of various (modern) retro computer platforms.

More like a benchmark of someone's programming skills in various retro computer platforms

For instance here:

https://github.com/SlithyMatt/multi-man ... elbrot.asm

Starting at top left corner, it visits the entire screen (from left to right, then again for the next row), to calculate and modify each attribute color. At every step, it spends some time to calculate the corresponding attribute address on screen.

Why?

It could simply start at attribute address 22528 and increment it at every step.

[danboid]

It looks like the asm files in the ZXN directory already have the correct SjASMPlus directives, so I was able to assemble just by running the build.sh file, but you could also invoke it directly:

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sjasmplus --lst zxn-mandelbrot.asm
sjasmplus --lst zxn-mandelbrot2.asm
sjasmplus --lst zxn-mandelbrot_127_63_15.asm
sjasmplus --lst zxn-mandelbrot_max_lores.asm
sjasmplus --lst zxn-mandelbrot_max_layer2.asm

If that doesn't work I can share the assembled .nex files.

build.sh file? Which build.sh file are you referring to?

I want to learn how to build this myself. I've just tried using --lst now but I get these errors:

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dan@zbook:~/src/multi-mandlebrot/Z80n$ sjasmplus --lst=mandelbrot.nex mandelbrot.asm
SjASMPlus Z80 Cross-Assembler v1.20.3 (https://github.com/z00m128/sjasmplus)
Pass 1 complete (0 errors)
Pass 2 complete (0 errors)
fixedpt.asm(175): error: Unrecognized instruction: mul d,e
fixedpt.asm(181): error: Unrecognized instruction: mul d,e
fixedpt.asm(186): error: Unrecognized instruction: mul d,e
fixedpt.asm(197): error: Unrecognized instruction: mul d,e
Pass 3 complete
Errors: 4, warnings: 0, compiled: 332 lines, work time: 0.002 seconds
dan@zbook:~/src/multi-mandlebrot/Z80n$ ls -l
total 56
-rw-rw-r-- 1 dan dan  5551 May 15 13:02 fixedpt24.asm
-rw-rw-r-- 1 dan dan  3518 May 15 13:02 fixedpt.asm
-rw-rw-r-- 1 dan dan  4122 May 15 13:02 mandelbrot24.asm
-rw-rw-r-- 1 dan dan  4052 May 15 13:02 mandelbrot.asm
-rw-rw-r-- 1 dan dan 15653 May 15 13:06 mandelbrot.lst
-rw-rw-r-- 1 dan dan 15653 May 15 13:08 mandelbrot.nex
dan@zbook:~/src/multi-mandlebrot/Z80n$ sjasmplus --lst=mandelbrot24.nex mandelbrot24.asm
SjASMPlus Z80 Cross-Assembler v1.20.3 (https://github.com/z00m128/sjasmplus)
Pass 1 complete (0 errors)
Pass 2 complete (0 errors)
fixedpt24.asm(207): error: Unrecognized instruction: mul d,e
fixedpt24.asm(212): error: Unrecognized instruction: mul d,e
fixedpt24.asm(220): error: Unrecognized instruction: mul d,e
fixedpt24.asm(229): error: Unrecognized instruction: mul d,e
fixedpt24.asm(242): error: Unrecognized instruction: mul d,e
fixedpt24.asm(252): error: Unrecognized instruction: mul d,e
fixedpt24.asm(259): error: Unrecognized instruction: mul d,e
fixedpt24.asm(269): error: Unrecognized instruction: mul d,e
Pass 3 complete
Errors: 8, warnings: 0, compiled: 640 lines, work time: 0.011 seconds

[danboid]

More like a benchmark of someone's programming skills in various retro computer platforms

For instance here:

https://github.com/SlithyMatt/multi-man ... elbrot.asm

Starting at top left corner, it visits the entire screen (from left to right, then again for the next row), to calculate and modify each attribute color. At every step, it spends some time to calculate the corresponding attribute address on screen.

Why?

It could simply start at attribute address 22528 and increment it at every step.

Please share you improved version and tell me how to build it.

Thanks

[danboid]

OK I think I've got them to build OK now

Code: Select all

dan@zbook:~/src/multi-mandlebrot/Z80n$ sjasmplus --zxnext --lst=mandelbrot.nex mandelbrot.asm
SjASMPlus Z80 Cross-Assembler v1.20.3 (https://github.com/z00m128/sjasmplus)
Pass 1 complete (0 errors)
Pass 2 complete (0 errors)
Pass 3 complete
Errors: 0, warnings: 0, compiled: 332 lines, work time: 0.002 seconds
dan@zbook:~/src/multi-mandlebrot/Z80n$ sjasmplus --zxnext --lst=mandelbrot24.nex mandelbrot24.asm
SjASMPlus Z80 Cross-Assembler v1.20.3 (https://github.com/z00m128/sjasmplus)
Pass 1 complete (0 errors)
Pass 2 complete (0 errors)
Pass 3 complete
Errors: 0, warnings: 0, compiled: 640 lines, work time: 0.003 seconds

[danboid]

Nope. That is not correct. When I try running one of those .nex files I get the error

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This is a ve.o file. Please update to the latest .nexload version.

Does anyone use sjasmplus under Linux who can tell me how I should be building these files? sjasmplus does not output a .nex file for me, not that I can see. I'm just told its compiled OK.

[ParadigmShifter]

You're only outputting a .lst file?

I tried that on my (speccy) code, this is the kind of thing it produces

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# file opened: sheet.asm
  1   0000              ; sjasmplus.exe --sym=out.sym --syntax=f --raw=out.bin sheet.asm
  2   0000
  3   0000              	DEVICE ZXSPECTRUM48
  4   0000
  5   0000              TIMING EQU 1
  6   0000
  7   0000              ORGADDR	EQU #8000
  8   0000
  9   0000              	ORG ORGADDR
 10   8000
 11   8000              	DISPLAY "ORIGIN ", /A, ORGADDR
 12   8000
 13   8000              main:
 14   8000              	IF TIMING
 15   8000 3E 01        	ld a, 1
 16   8002 D3 FE        	out (#fe), a
 17   8004              	ENDIF
 18   8004

which is not executable code.

You probably want something like --raw=out.bin to produce a binary file?

EDIT: Ok you probably need to use SAVENEX at the end of your file but I can't really help with that since I don't know about the Next binary format.

[flatduckrecords]

Ah, I see the problem @danboid, you're looking in the Z80n directory, but those are just partial files, meant to be INCLUDE'd within another asm file.

The directory called zxn is the one you need. That contains the .asm files that can be assembled. The build script is in there as well!

[Einar Saukas]

Please share you improved version and tell me how to build it.

Replace file "zxs-mandelbrot.asm" with this:

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   DEVICE ZXSPECTRUM48

   org $8000

start:
   jp init

color_codes:
   db 8,16,24,32,40,48,56,72
   db 80,88,96,104,112,120,0

   include "../Z80/mandelbrot.asm"

ROM_CLS           = $0DAF

COLOR_MAP         = $5800


i_result: db 0

init:
   di
   exx                  ; save hl' register on stack
   push hl              ; to correct return into basic
   call ROM_CLS
   ld bc,0              ; X = 0, Y = 0
   LD DE,COLOR_MAP-1
   PUSH DE              ; SAVE ATTRIBUTE ADDRESS
.loopm:
   call mand_get
   POP DE
   INC DE               ; NEXT ATTRIBUTE ADDRESS
   PUSH DE
   ld hl,color_codes
   add a,l              ; HL = I
   ld l,a
   ld a,(hl)            ; A = color code for I
   ld (de),a            ; set color code
   inc b                ; increment X
   BIT 5,B
   JP Z,.loopm          ; loop until X = width
   ld b,0               ; X = 0
   inc c                ; increment Y
   ld a,MAND_HEIGHT
   cp c
   jp nz,.loopm         ; loop until Y = height
   POP DE               ; DISCARD ATTRIBUTE ADDRESS
   pop hl               ; restore hl' register
   exx                  ; from stack
   ei
   ret


; Deployment
LENGTH      = $ - start

; option 1: tape
   include TapLib.asm
   MakeTape ZXSPECTRUM48, "man48.tap", "man48", start, LENGTH, start

; option 2: snapshot
   SAVESNA "man48.sna", start

All changes in capital letters. Not tested but it should work

Based on a quick look at the other files, there's a lot to optimize there too...

[danboid]

Ah, I see the problem @danboid, you're looking in the Z80n directory, but those are just partial files, meant to be INCLUDE'd within another asm file.

The directory called zxn is the one you need. That contains the .asm files that can be assembled. The build script is in there as well!

That was my problem. I never spotted the zxn dir and presumed it was the z80n dir I was trying the build. Thanks flatduckrecords!

The .asm files in the zxn dir successfully output .nex binaries that actually run and you can build them just by just running `sjasmplus` with no extra options required apart from the name of the .asm file to build.

Easy peasy when you use the right files!

[danboid]

Replace file "zxs-mandelbrot.asm" with this:

Code: Select all

   DEVICE ZXSPECTRUM48

   org $8000

start:
   jp init

color_codes:
   db 8,16,24,32,40,48,56,72
   db 80,88,96,104,112,120,0

   include "../Z80/mandelbrot.asm"

ROM_CLS           = $0DAF

COLOR_MAP         = $5800


i_result: db 0

init:
   di
   exx                  ; save hl' register on stack
   push hl              ; to correct return into basic
   call ROM_CLS
   ld bc,0              ; X = 0, Y = 0
   LD DE,COLOR_MAP-1
   PUSH DE              ; SAVE ATTRIBUTE ADDRESS
.loopm:
   call mand_get
   POP DE
   INC DE               ; NEXT ATTRIBUTE ADDRESS
   PUSH DE
   ld hl,color_codes
   add a,l              ; HL = I
   ld l,a
   ld a,(hl)            ; A = color code for I
   ld (de),a            ; set color code
   inc b                ; increment X
   BIT 5,B
   JP Z,.loopm          ; loop until X = width
   ld b,0               ; X = 0
   inc c                ; increment Y
   ld a,MAND_HEIGHT
   cp c
   jp nz,.loopm         ; loop until Y = height
   POP DE               ; DISCARD ATTRIBUTE ADDRESS
   pop hl               ; restore hl' register
   exx                  ; from stack
   ei
   ret


; Deployment
LENGTH      = $ - start

; option 1: tape
   include TapLib.asm
   MakeTape ZXSPECTRUM48, "man48.tap", "man48", start, LENGTH, start

; option 2: snapshot
   SAVESNA "man48.sna", start

All changes in capital letters. Not tested but it should work

Based on a quick look at the other files, there's a lot to optimize there too...

Thanks but I'm only really bothered about the Next version and it seems you optimsed the Speccy 48k version.

[danboid]

When I run one of these fractal drawing .nex binaries, is there a key combo that will let me return to the zxn command prompt when its finished drawing or is rebooting my only option?

It could do with printing out the time took to draw the fractal. That could be my first z80 asm project if it doesn't already do that already.

[Einar Saukas]

Thanks but I'm only really bothered about the Next version and it seems you optimsed the Speccy 48k version.

That's the file I indicated in my first post.

You could have mentioned you were not interested in this file, when you asked for the improved version of this file!