Add instructions for running this in Termux on Android

Also update the scripts to all support a QEMU_ARGS env variable so that
on android we can set the necessary args. Probably eventually someone
else will want to use that var too.

README.md

@@ -109,6 +109,37 @@ the call, but you can open up that file and try out the other commands too.
     2. Choose either the user or system-wide Path variable and add both `C:\Program Files\NASM` & `C:\Program Files\qemu`
  4. `boot.bat bootstrap-lisp.asm` (alternatively you can use the bash script in the git bash prompt)
 
+#### Android
+
+ 1. Install [Termux](https://play.google.com/store/apps/details/id=com.termux)
+    from the play store (or f-droid)
+
+ 2. Install qemu and the assembler, and git to clone the repo
+    `pkg install x11-repo && pkg install qemu-system-x86-64 nasm git`
+
+ 3. (Optional) Set up X11 for graphical display
+
+    1. Install the Termux X11 apk from
+       https://github.com/termux/termux-x11/releases (you most likely need the
+       arm64 one), or from f-droid
+    2. In the Termux X11 app settings configure the output display resolution
+       mode to custom and the resolution to 720x480
+    3. Install the necessary packages in the main Termux app:
+       `pkg install termux-x11-nightly`
+
+ 4. Clone bootstrap-os `git clone https://github.com/fsmv/bootstrap-os.git && cd bootstrap-os`
+
+ 5. To run in Termux:
+    1. `export QEMU_ARGS=-display gtk,show-menubar=off -L /data/data/com.termux/files/usr/share/qemu"`
+       If you like you can put this in `~/.bashrc` to save it
+    2. `termux-x11 :0 -xstartup "./boot bootstrap-lisp.asm"`
+       - Alternatively (if you didn't install the X11 app) you can run:
+         `./test -DHEADLESS lisp/tester.asm`
+         it will print the test results using the qemu debug console feature.
+
+I tried to run the debugger but I wasn't able to install a version of gdb that
+understands x86 in Termux (it only does arm) so debugging won't work.
+
 ## Reference Manuals
 
 This project depends on the

boot

@@ -10,4 +10,4 @@ name="${file%%.*}"
 binfile="bin/$name.bin"
 
 mkdir -p `dirname $binfile`
-nasm $file -f bin -o $binfile ${@:1:$(($#-1))} && qemu-system-x86_64 -drive file=$binfile,format=raw,if=ide
+nasm $file -f bin -o $binfile ${@:1:$(($#-1))} && qemu-system-x86_64 $QEMU_ARGS -drive file=$binfile,format=raw,if=ide

debug

@@ -60,11 +60,11 @@ nasm $bit16file -f elf32 -F dwarf -g -w+gnu-elf-extensions -o $elffile ${@:1:$((
 rm $bit16file
 
 if ! which qemu-system-i386 > /dev/null; then
-  printf "\nYou need to install qemu-arch-extra to use the debugger\n"
+  printf "\nYou need to install qemu-system-i386 (qemu-arch-extra package in some distributions) to use the debugger\n"
   exit 127
 fi
 
-qemu-system-i386 -s -S -drive file=$binfile,format=raw,if=ide &
+qemu-system-i386 $QEMU_ARGS -s -S -drive file=$binfile,format=raw,if=ide &
 
 # Note: If you turn off the offset for the add-symbol-file command then gdb can
 # load the source code line numbers correctly but the fancy real-mode-gdb config

test

@@ -5,10 +5,6 @@ if [ "$#" -eq 0 ]; then
     exit 1
 fi
 
-if [ -z "$QEMU" ]; then
-  QEMU="qemu-system-x86_64"
-fi
-
 file=${@: -1}
 name="${file%%.*}"
 binfile="bin/$name.bin"
@@ -21,7 +17,7 @@ fi
 PID=$$
 compile() {
   nasm $file -f bin -o $binfile -DDEBUGCON ${@:2:$(($#-2))} && \
-    $QEMU $HEADLESS_ARGS -debugcon stdio -drive file=$binfile,format=raw,if=ide
+    qemu-system-x86_64 $QEMU_ARGS $HEADLESS_ARGS -debugcon stdio -drive file=$binfile,format=raw,if=ide
   # Kill the process if we had a compile error so that we exit with non-zero
   # status even though we used a pipe which exits with the tee status
   ERR=$?