Implement support for filesystem calls

This includes stdio fopen/fread/fseek/fclose, as well as the
posix open/read/lseek/close/fstat.
These use a very simple read only filesystem format. A tool
is included to create these filesystem images.

I've changed sceneview and DOOM to use this instead of reading
directly from the block device. w_wad from DOOM is just pulled
from the mainline (with a few tweaks), replacing the heavily
hacked version I was using previously.

Makefile

@@ -20,6 +20,7 @@ JAVAC := $(shell which javac)
 all:
 	cd tools/emulator && make
 	cd tools/serial_boot && make
+	cd tools/mkfs && make
 	cd rtl/ && make
 	cd software/libs/libc && make
 	cd software/libs/librender && make
@@ -36,6 +37,7 @@ test: all FORCE
 clean:
 	cd tools/emulator && make clean
 	cd tools/serial_boot && make clean
+	cd tools/mkfs && make clean
 	cd software/libs/libc && make clean
 	cd software/libs/librender && make clean
 	cd software/libs/libos && make clean

software/apps/doom/Makefile

@@ -94,19 +94,22 @@ $(O)/doom.hex:	$(OBJS)
 	$(ELF2HEX) -o $(O)/doom.hex -b 0 $(O)/doom.elf
 	$(OBJDUMP) --disassemble $(O)/doom.elf > doom.lst 2> /dev/null
 
-run: $(O) $(O)/doom.hex
-	../../../bin/emulator -f 640x400  -b doom1.wad obj/doom.hex
+run: $(O) $(O)/doom.hex fsimage.bin
+	../../../bin/emulator -f 640x400  -b fsimage.bin obj/doom.hex
 
-debug: $(O) $(O)/doom.hex
-	../../../bin/emulator -m gdb -f 640x400  -b doom1.wad obj/doom.hex &
+debug: $(O) $(O)/doom.hex fsimage.bin
+	../../../bin/emulator -m gdb -f 640x400  -b fsimage.bin obj/doom.hex &
 	/usr/local/llvm-nyuzi/bin/lldb --arch nyuzi $(O)/doom.elf -o "gdb-remote 8000"
 
-verirun: $(O)  $(O)/doom.hex
-	../../../bin/verilator_model +bin=obj/doom.hex +block=doom1.wad
+verirun: $(O)  $(O)/doom.hex fsimage.bin
+	../../../bin/verilator_model +bin=obj/doom.hex +block=fsimage.bin
 
 fpgarun: $(O)/doom.hex
 	../../../bin/serial_boot $(SERIAL_PORT) $(O)/doom.hex
 
+fsimage.bin: doom1.wad
+	../../../bin/mkfs fsimage.bin DOOM1.WAD
+
 $(O)/%.o:	%.c
 	$(CC) $(CFLAGS) -c $< -o $@
 

software/apps/doom/README.md

@@ -6,22 +6,16 @@ compiled to 300k).
 
 A shareware WAD file is required to use this. This is not included in this
 repository, but can be found pretty easily with a Google search. It should be 
-named "doom1.wad" and placed in this directory.
+named "DOOM1.WAD" (case sensitive) and placed in this directory.
 
 To run (in the emulator) type 'make run'.  This does not currently run on FPGA
 because there isn't a mass storage device to store the WAD.
 
 The primary changes I made for the port were:
 
-* In w_wad.c, read the WAD file directly from a simulated block device. Since 
-this is running on bare metal with a minimal libc, there is no filesystem layer. 
-I commented out other code that interacted with the filesystem (for example, 
-saving and restoring games). The size of the WAD file is hardcoded in this file.
 * in i_video.c, added code to copy the screen to the framebuffer, expanding 
 from an 8 bit paletted format to the 32 bit per pixel framebuffer format.
 * in i_video.c, reads from a virtual keyboard device for input.
-* Fixed some places that made bad assumptions that the hardware supported 
-unaligned memory accesses.
-* Code from i_net and i_sound mostly removed, since there's no support for 
-them.
+* W_CheckNumForName assumes support for unaligned accesses, changed to use memcmp.
+* Code from i_net and i_sound removed, since there's no support for them.