Modifying luac to build and run as a ps-exe

.github/workflows/build.yml

@@ -0,0 +1,55 @@
+name: Build
+
+on:
+  push:
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    container: ghcr.io/grumpycoders/pcsx-redux-build:latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Nugget
+        # Checked out rather than vendored: nugget's psyqo-lua consumes psxlua,
+        # so a submodule here would close a dependency cycle.
+        uses: actions/checkout@v4
+        with:
+          repository: pcsx-redux/nugget
+          path: nugget
+
+      - name: Library
+        run: make -C src psx -j2
+
+      - name: Library without the parser
+        run: |
+          make -C src clean
+          make -C src psx-noparser -j2
+
+      - name: Compiler
+        run: |
+          make -C src clean
+          make -C src psx-luac NUGGET=$GITHUB_WORKSPACE/nugget -j2
+
+      - name: pcsx-redux
+        # --appimage-extract rather than mounting it: the runner has no FUSE.
+        run: |
+          curl -sL -o pcsx-redux.zip https://distrib.app/pub/org/pcsx-redux/project/dev-linux-x64/latest
+          unzip -q pcsx-redux.zip
+          ./PCSX-Redux-*.AppImage --appimage-extract > /dev/null
+
+      - name: Compile a script on the console
+        # pcsx-redux brings SDL video up even under -testmode, which is why
+        # pcsx-redux's own CI runs its tests under xvfb-run.
+        run: xvfb-run tests/run-luac.sh "$GITHUB_WORKSPACE/squashfs-root/AppRun"
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: luac.ps-exe
+          path: src/luac.ps-exe

.gitignore

@@ -0,0 +1,8 @@
+*.o
+*.a
+luac
+lua
+*.ps-exe
+*.elf
+*.map
+*.dep

README

@@ -8,18 +8,33 @@ further information about Lua, see doc/readme.html.
 
 This version of Lua has been modified to work on the Sony PlayStation 1.
 
-There are now only three platforms available for compilation:
+There are now only four platforms available for compilation:
 - `psx`: This platform is used to compile Lua for the Sony PlayStation 1. This
   will only generate a library file named "liblua.a". The binary footprint of
   this library will be roughly 110kB.
 - `psx-noparser`: This platform is used to compile Lua for the Sony PlayStation
   1 without the parser. Only precompiled bytecode can be loaded by this version.
   This will only generate a library file named "liblua-noparser.a". The binary
   footprint of this library will be roughly 85kB.
+- `psx-luac`: This platform builds the Lua compiler itself as a ps-exe, named
+  "luac.ps-exe". Running the compiler on the target is what makes its bytecode
+  a sure thing: the number representation, the pointer size and the endianness
+  are the target's by construction rather than by a matching host build.
 - `host32`: This platform is used to compile Lua for a 32-bit host system. This
-  will generate the Lua interpreter (lua) and the lua compiler (luac). The
-  compiler should be able to generate bytecode that can be run on the Sony
-  PlayStation 1.
+  will generate the Lua interpreter (lua). It no longer generates the compiler;
+  use `psx-luac` for that, since a 32-bit host build is not available in most
+  environments any more.
+
+The `psx-luac` platform is the only part of this repository that needs nugget,
+and it is not vendored: nugget's psyqo-lua consumes psxlua, so a submodule here
+would close a dependency cycle. Point NUGGET at a checkout instead.
+
+    make -C src psx-luac NUGGET=/path/to/nugget
+
+luac.ps-exe reads its arguments from unmapped memory at 0x40000000 and does its
+file I/O over PCDRV, so it runs under an emulator that serves both. src/args.lua
+is the pcsx-redux side: call createArgsBuffer() with the arguments you would
+have passed on a command line, and load it alongside the executable.
 
 The following key differences exist between the original Lua 5.2.4 and this
 version of Lua:

src/Makefile

@@ -53,7 +53,7 @@ MYOBJS=
 
 # == END OF USER SETTINGS -- NO NEED TO CHANGE ANYTHING BELOW THIS LINE =======
 
-PLATS= host32 psx psx-noparser
+PLATS= host32 psx psx-noparser psx-luac
 
 ifeq ($(NOPARSER),true)
 LUA_A=	liblua-noparser.a
@@ -78,8 +78,8 @@ LUA_O=	lua.o
 LUAC_T=	luac
 LUAC_O=	luac.o
 
-ALL_O= $(BASE_O) $(LUA_O) $(LUAC_O)
-ALL_T= $(LUA_A) $(LUA_T) $(LUAC_T)
+ALL_O= $(BASE_O) $(LUA_O)
+ALL_T= $(LUA_A) $(LUA_T)
 ALL_A= $(LUA_A)
 
 # Targets start here.
@@ -98,11 +98,9 @@ $(LUA_A): $(BASE_O)
 $(LUA_T): $(LUA_O) $(LUA_A)
 	$(CC) -o $@ $(LDFLAGS) $(LUA_O) $(LUA_A) $(LIBS)
 
-$(LUAC_T): $(LUAC_O) $(LUA_A)
-	$(CC) -o $@ $(LDFLAGS) $(LUAC_O) $(LUA_A) $(LIBS)
-
 clean:
 	$(RM) $(ALL_T) $(ALL_O) $(ALL_A) liblua-noparser.a lnoparser.o
+	$(RM) $(LUAC_T) $(LUAC_O) psx-heap.o psx-glue.o luac.elf luac.map luac.ps-exe *.dep
 
 depend:
 	@$(CC) $(CFLAGS) -MM l*.c
@@ -132,6 +130,9 @@ psx:
 psx-noparser:
 	$(MAKE) a TARGET=psx NOPARSER=true
 
+psx-luac: psx
+	$(MAKE) -f luac-psx.mk
+
 # list targets that do not create files (but not all makes understand .PHONY)
 .PHONY: all $(PLATS) default o a clean depend echo none
 

src/args.lua

@@ -0,0 +1,33 @@
+local ffi = require 'ffi'
+local uint8_t = ffi.typeof 'uint8_t[?]'
+local argsBuffer
+local processName = 'luac.ps-exe'
+
+function createArgsBuffer(...)
+    local args = { ... }
+    local spaceNeeded = #processName + 2
+    for i, v in ipairs(args) do
+        local a = tostring(v)
+        spaceNeeded = spaceNeeded + #a + 1
+    end
+    argsBuffer = ffi.new(uint8_t, spaceNeeded)
+    local ptr = ffi.cast('uint8_t *', argsBuffer)
+    ffi.copy(ptr, processName)
+    ptr = ptr + #processName + 1
+    for i, v in ipairs(args) do
+        local a = tostring(v)
+        ffi.copy(ptr, a)
+        ptr = ptr + #a + 1
+    end
+    ptr[0] = 0
+end
+
+function UnknownMemoryRead(address, size)
+    if size ~= 1 then return 0xffffffff end
+    local offset = address - 0x40000000
+    if offset < 0 then return 0xff end
+    if offset >= ffi.sizeof(argsBuffer) then return 0xff end
+    return argsBuffer[offset]
+end
+
+createArgsBuffer()

src/luac-psx.mk

@@ -0,0 +1,35 @@
+# Builds luac as a ps-exe, so the compiler runs on the console (or in an
+# emulator) instead of on the host. Input and output go through PCDRV, and
+# argv is read from unmapped memory at 0x40000000 - see args.lua.
+#
+# psxlua does not depend on nugget: nugget's psyqo-lua consumes psxlua, so
+# vendoring it here would close a cycle. Point NUGGET at a checkout instead.
+#
+#   make psx-luac NUGGET=/path/to/nugget
+#
+# liblua.a must be built for the same target first; the psx-luac rule in
+# Makefile does that for you.
+
+ifeq ($(strip $(NUGGET)),)
+$(error NUGGET is not set - point it at a nugget checkout, e.g. make psx-luac NUGGET=../../nugget)
+endif
+
+TARGET = luac
+TYPE = ps-exe
+
+SRCS = \
+luac.c \
+psx-heap.c \
+psx-glue.s \
+$(NUGGET)/common/syscalls/printf.s \
+$(NUGGET)/common/crt0/memory-s.s \
+$(NUGGET)/common/crt0/memory-c.c \
+
+LIBRARIES = liblua.a
+
+CPPFLAGS += -I. -DLUA_COMPAT_ALL
+
+include $(NUGGET)/common.mk
+
+liblua.a:
+	$(MAKE) -f Makefile a TARGET=psx