ped7g’s gists

ped7g / zexallsj.asm

Created August 23, 2021 18:18

zexdoc.z80 and zexall.z80 patched for sjasmplus v1.18.2 - produce identical .com binary except padding bytes being zeroed

	; the macro syntax is impossible to patch from outside (the "&" operators for label/arguments),
	; so macros had been hard-edited to sjasmplus syntax. Other incompatible lines are amended
	; through DEFINEs and OPT adjusting sjasmplus parsing

	; some defines to change unknown syntax/decorations to nothing or silent assert to ignore them
	DEFINE title assert 1,
	DEFINE aseg
	DEFINE local assert 1,
	DEFINE error assert 0,

ped7g / short_nr_init.asm

Created April 8, 2021 06:41

ZX Spectrum Next - size optimised setup of larger block of next-registers

	; Author: Ped7g ; (C) 2021 ; license: https://opensource.org/licenses/MIT
	; Z80N (ZX Next) assembly, sjasmplus syntax: https://github.com/z00m128/sjasmplus
	;
	; code-size optimisation for larger next-reg init block, where `nextreg r,v` ED91rrvv
	; opcode takes four bytes for every next-reg set, so a block of 20 pair values takes
	; 80 bytes (with the "setup_next_regs_v2" approach such block will take only 58 bytes)

	;----------------------------------------------------------------------------------------
	; variant 1, reads next-reg pairs from particular memory address
	; this will break-even at 8 value pairs, every one more pair is two byte less

ped7g / AllanTurveyCheckerboard.asm

Created February 15, 2021 22:54

ZX Spectrum Z80 asm - Attribute brightness checkerboard routine, optimized to size (32B)

	; Author: Ped7g ; (C) 2021 ; license: https://opensource.org/licenses/MIT
	; Z80 assembly, syntax for sjasmplus: https://github.com/z00m128/sjasmplus
	; to build: sjasmplus AllanTurveyCheckerboard.asm
	OPT --syntax=abf : DEVICE ZXSPECTRUM48,31999 : ORG $8000

	; D:E = field height:width, A = attribute, modifies: AF, HL, BC, IXL
	drawCheckerboard:
	ld hl,$5800
	.alternateLine
	xor $40 ; alternate BRIGHT 1

ped7g / omega_fades_2.asm

Last active February 3, 2021 20:38

ZX Spectrum fade-in/fade-out effects using attributes, focusing on small code size (second version)

	; Authors: Omega, Ped7g, Baze ; (C) 2021 ; license: https://opensource.org/licenses/MIT
	; Z80 assembly, syntax for sjasmplus: https://github.com/z00m128/sjasmplus
	; to assemble run: sjasmplus omega_fades_2.asm
	OPT --syntax=abf
	DEVICE ZXSPECTRUM48,31999
	ORG $8000

	; uncomment and set to available SCR file to run the effect on ZX screen image (6912 bytes)
	; DEFINE SCR_FILE "diver - Mercenary 4. The Heaven's Devil (2014) (Forever 2014 Olympic Edition, 1).scr"

ped7g / ped_base64.asm

Last active September 18, 2022 18:53

linux x86_64 asm example of "base64 encoder" (for lecturing purposes)

	; (C) [copyleft] 2021 Peter Helcmanovsky
	; License: CC0 https://creativecommons.org/share-your-work/public-domain/cc0
	;
	; x86_64 linux asm example of base64 encoding
	;
	; reads stdin, encodes it to base64 without new-lines, outputs to stdout
	;
	; the code is meant to be rather straightforward and simple (for lecturing purpose),
	; not performance optimal
	;

ped7g / omega_fades.asm

Last active January 12, 2021 19:12

ZX Spectrum fade-in/fade-out effects using attributes, focusing on small code size (no tables used)

	; Authors: Omega, Ped7g, Baze ; (C) 2021 ; license: https://opensource.org/licenses/MIT
	; Z80 assembly, syntax for sjasmplus: https://github.com/z00m128/sjasmplus
	; to assemble run: sjasmplus omega_fades.asm
	OPT --syntax=abf
	DEVICE ZXSPECTRUM48,31999
	ORG $8000

	;------------------------------------------------------------------------------
	; ULA attributes "fade out" effect, going through PAPER/INK values,
	; decrements them (individually) by 1 every iteration (call of routine)

ped7g / asterisk_vs_exclamation_char.asm

Created January 10, 2021 09:27

	; to assemble: sjasmplus asterisk_vs_exclamation_char.asm
	DEVICE ZXSPECTRUM48,31999 : OPT --zxnext

	ORG $8000
	font:
	ASSERT 0 == high(font) % 8 ; must reside at aligned-enough address to fit this
	ds '!'*8,0 ; don't bother to define other chars, go to exclamation mark
	dg ---##---
	dg ---##---
	dg ---##---

ped7g / color8vs9b.asm

Created October 27, 2020 02:34

ZX Spectrum Next - show how 8bit defined colors expand the two "BB" bits to full 9bit color definition

	; show how 8-bit color values RRRGGGBB are being extended to full 9-bit definition
	; displays blue squares with 8bit blue part 0, 1, 2, 3 (all possible blue shades in 8b)
	; and under them the 9bit defined blues as %000, %011, %101, %111 (how 8b extends to 9b)
	; assembling: sjasmplus color8vs9b.asm ( https://github.com/z00m128/sjasmplus )

	DEVICE ZXSPECTRUMNEXT : OPT --syntax=abfw
	ORG $8000
	start:
	di
	ld a,7

ped7g / flipULA2.asm

Last active January 22, 2025 21:46

ZX Spectrum Next - ULA double buffering example v2 (advanced techniques: DMA + custom IM1 interrupt)

	DEFINE USE_DMA_TO_CLEAR_SCREEN ; comment out to get LDIR clear version
	DEFINE USE_DOUBLE_BUFFERING ; comment out to see single-buffer redraw issues

	DEVICE ZXSPECTRUMNEXT

	BORDER MACRO color?
	ld a,color?
	out (254),a
	ENDM

ped7g / flipULA.asm

Last active February 3, 2021 20:40

ZX Spectrum Next - ULA double buffering example

	DEVICE ZXSPECTRUMNEXT
	ORG $8000 ; this example does map Bank5/Bank7 ULA to $4000 (to use "pixelad" easily)
	mainLoop:
	call FlipULABuffers ; flip the buffer screen to visible screen and flip buffer
	call drawDot
	jr mainLoop

	FlipULABuffers: ; Flip ULA/Alt ULA screen (double buffer ULA screen)
	; ret ; uncomment to see effect of non-double-buffered running (blinking dots)
	ld a,(ULABank) ; Get screen to display this frame

Peter Ped Helcmanovsky ped7g