From e007e1c95912e17f33ed135b4b69d293076a7017 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Sun, 14 Nov 2021 13:56:59 +0000
Subject: [PATCH] Add a ZX81 port.

It seems that ZX81 emulators are awful.  This hack is the best I could
come up with.

Since I wrote the thing in ZX BASIC in an emulator, I guess
`zx81-loader.p' file is the preferred form for modification.
---
 .gitignore    |   1 +
 Makefile      |   8 ++++++++
 gluep         |  43 +++++++++++++++++++++++++++++++++++++++++++
 zx81-loader.p | Bin 0 -> 929 bytes
 zx81.s        |  25 +++++++++++++++++++++++++
 5 files changed, 77 insertions(+)
 create mode 100755 gluep
 create mode 100644 zx81-loader.p
 create mode 100644 zx81.s

diff --git a/.gitignore b/.gitignore
index 6477f1c..aff1ece 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 *.img
 /spectrum-fizzbuzz.tap
+/zx81-fizzbuzz.p
diff --git a/Makefile b/Makefile
index 0af35b7..40594c4 100644
--- a/Makefile
+++ b/Makefile
@@ -16,6 +16,14 @@ spectrum-fizzbuzz.tap: tapify spectrum-loader.tap spectrum-fb.img
 	  ./tapify 3 fb 0x7000 0x8000 <spectrum-fb.img; } \
 		>$@.new && mv $@.new $@
 
+CLEANFILES		+= zx81-fb.img
+zx81-fb.img: zx81.s fizzbuzz.s
+	z80asm -o $@ $^
+
+TARGETS			+= zx81-fizzbuzz.p
+zx81-fizzbuzz.p: gluep zx81-loader.p zx81-fb.img
+	./gluep 0x4009:zx81-loader.p 0x7000:zx81-fb.img >$@.new && mv $@.new $@
+
 all: $(TARGETS)
 
 clean::; rm -f $(CLEANFILES)
diff --git a/gluep b/gluep
new file mode 100755
index 0000000..504c779
--- /dev/null
+++ b/gluep
@@ -0,0 +1,43 @@
+#! /usr/bin/perl
+
+use autodie;
+
+sub intify ($) {
+  my ($n) = @_;
+  if ($n =~ /^0/) { $n = oct $n; }
+  return $n;
+}
+
+my $MEM = "";
+my $BASE = 0x4009;
+my $LIMIT = 0x8000;
+
+for my $a (@ARGV) {
+  $a =~ /^(\w+):(.*)$/ or die "bad spec ADDR:FILE";
+  my $addr = intify $1;
+  my $file = $2;
+
+  my $body = "";
+  open my $fh, "<", $file;
+  READ: for (;;) {
+    sysread $fh, my $buf, 4096;
+    last READ unless length $buf;
+    $body .= $buf;
+  }
+  close $fh;
+
+  $addr >= $BASE && $LIMIT >= $addr + length $body
+    or die "out of bounds";
+
+  $addr -= $BASE;
+  my $end = $addr + length $body;
+  my $before = $addr > length $MEM
+    ? $MEM . "\0" x ($addr - length $MEM)
+    : substr $MEM, 0, $addr;
+  my $after = $end <= length $MEM
+    ? ""
+    : substr $MEM, $end;
+  $MEM = $before . $body . $after;
+}
+
+syswrite STDOUT, $MEM;
diff --git a/zx81-loader.p b/zx81-loader.p
new file mode 100644
index 0000000000000000000000000000000000000000..77d7287a0c990384cbcf4563a98318527d86395d
GIT binary patch
literal 929
zcmZQzVCZ+4;IP7(fnlZdb|AUKd51GYtOElR1H=FS|IPay7(k$x2TU>SQIu$auyB)Q
w5UCa*)v^GqGA=%bpI78ml$7P_`V)XE%Ai`XDh3OVDu9H|XgG|laA^1e04Ka4pa1{>

literal 0
HcmV?d00001

diff --git a/zx81.s b/zx81.s
new file mode 100644
index 0000000..8efe185
--- /dev/null
+++ b/zx81.s
@@ -0,0 +1,25 @@
+;;; -*-asm-*-
+
+	org	0x7000
+
+spc:	equ	0
+
+fixdig:	macro
+	add	a, 0x1c
+	endm
+
+print_a: macro
+	rst	0x10
+	endm
+
+endstr:	equ	0x7a
+endstrp: macro
+	cp	endstr
+	endm
+
+	jr	begin
+
+fizz:	db	0x2b, 0x2e, 0x3f, 0x3f, endstr
+buzz:	db	0x27, 0x3a, 0x3f, 0x3f, endstr
+
+begin:
-- 
2.11.0