#
# This makefile system follows the structuring conventions
# recommended by Peter Miller in his excellent paper:
#
#	Recursive Make Considered Harmful
#	http://aegis.sourceforge.net/auug97.pdf
#
OBJDIR := obj

# Run 'make V=1' to turn on verbose commands, or 'make V=0' to turn them off.
ifeq ($(V),1)
override V =
endif
ifeq ($(V),0)
override V = @
endif

-include conf/env.mk

LABSETUP ?= ./

TOP = .

# try to generate a unique GDB port
GDBPORT	:= $(shell expr `id -u` % 5000 + 25000)

CC	:= $(GCCPREFIX)gcc -pipe
AS	:= $(GCCPREFIX)as
AR	:= $(GCCPREFIX)ar
LD	:= $(GCCPREFIX)ld
OBJCOPY	:= $(GCCPREFIX)objcopy
OBJDUMP	:= $(GCCPREFIX)objdump
NM	:= $(GCCPREFIX)nm

QEMU = /home/course/csci352/bin/qemu-system-i386

# Native commands
NCC	:= gcc $(CC_VER) -pipe
NATIVE_CFLAGS := $(CFLAGS) $(DEFS) $(LABDEFS) -I$(TOP) -MD -Wall
TAR	:= tar
PERL	:= perl

# Compiler flags
# -fno-builtin is required to avoid refs to undefined functions in the kernel.
# Only optimize to -O1 to discourage inlining, which complicates backtraces.
CFLAGS := $(CFLAGS) $(DEFS) $(LABDEFS) -O1 -fno-builtin -I$(TOP) -MD
CFLAGS += -fno-omit-frame-pointer
CFLAGS += -std=gnu99
CFLAGS += -static
CFLAGS += -Wall -Wno-format -Wno-unused -Werror -m32
# -fno-tree-ch prevented gcc from sometimes reordering read_ebp() before
# mon_backtrace()'s function prologue on gcc version: (Debian 4.7.2-5) 4.7.2
CFLAGS += -fno-tree-ch

# prevent relative addressing and dynamic linking
CFLAGS += -fno-pic -fno-pie

# Add -fno-stack-protector if the option exists.
CFLAGS += $(shell $(CC) -fno-stack-protector -E -x c /dev/null >/dev/null 2>&1 && echo -fno-stack-protector)

# Common linker flags
LDFLAGS := -m elf_i386
# this can cause some strange behavior with GNU ld for some reason
#LDFLAGS += -no-pie

# Linker flags for JOS user programs
ULDFLAGS := -T user/user.ld

GCC_LIB := $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)

# Lists that the */Makefrag makefile fragments will add to
OBJDIRS :=

# Make sure that 'all' is the first target
all:

# Eliminate default suffix rules
.SUFFIXES:

# Delete target files if there is an error (or make is interrupted)
.DELETE_ON_ERROR:

# make it so that no intermediate .o files are ever deleted
.PRECIOUS: %.o $(OBJDIR)/boot/%.o $(OBJDIR)/kern/%.o \
	   $(OBJDIR)/lib/%.o $(OBJDIR)/fs/%.o $(OBJDIR)/net/%.o \
	   $(OBJDIR)/user/%.o

KERN_CFLAGS := $(CFLAGS) -DJOS_KERNEL
USER_CFLAGS := $(CFLAGS) -DJOS_USER

# Update .vars.X if variable X has changed since the last make run.
#
# Rules that use variable X should depend on $(OBJDIR)/.vars.X.  If
# the variable's value has changed, this will update the vars file and
# force a rebuild of the rule that depends on it.
$(OBJDIR)/.vars.%: FORCE
	$(V)echo "$($*)" | cmp -s $@ || echo "$($*)" > $@
.PRECIOUS: $(OBJDIR)/.vars.%
.PHONY: FORCE


# Include Makefrags for subdirectories
include boot/Makefrag
include kern/Makefrag


QEMUOPTS = -drive file=$(OBJDIR)/kern/kernel.img,index=0,media=disk,format=raw -serial mon:stdio -gdb tcp::$(GDBPORT)
QEMUOPTS += $(shell if $(QEMU) -nographic -help | grep -q '^-D '; then echo '-D qemu.log'; fi)
IMAGES = $(OBJDIR)/kern/kernel.img
QEMUOPTS += $(QEMUEXTRA)

.gdbinit: gdbinit.tmpl
	sed "s/localhost:1234/localhost:$(GDBPORT)/" < $^ > $@

gdb:
	gdb -q -n -x .gdbinit

pre-qemu: .gdbinit

qemu: $(IMAGES) pre-qemu
	$(QEMU) $(QEMUOPTS)

qemu-nox: $(IMAGES) pre-qemu
	@echo "***"
	@echo "*** Use Ctrl-a x to exit qemu"
	@echo "***"
	$(QEMU) -nographic $(QEMUOPTS)

qemu-gdb: $(IMAGES) pre-qemu
	@echo "***"
	@echo "*** Now run 'make gdb'." 1>&2
	@echo "***"
	$(QEMU) $(QEMUOPTS) -S

qemu-nox-gdb: $(IMAGES) pre-qemu
	@echo "***"
	@echo "*** Now run 'make gdb'." 1>&2
	@echo "***"
	$(QEMU) -nographic $(QEMUOPTS) -S

print-qemu:
	@echo $(QEMU)

print-gdbport:
	@echo $(GDBPORT)

# For deleting the build
clean:
	rm -rf $(OBJDIR) .gdbinit jos.in qemu.log

realclean: clean

distclean: realclean
	rm -rf conf/gcc.mk

# This magic automatically generates makefile dependencies
# for header files included from C source files we compile,
# and keeps those dependencies up-to-date every time we recompile.
# See 'mergedep.pl' for more information.
$(OBJDIR)/.deps: $(foreach dir, $(OBJDIRS), $(wildcard $(OBJDIR)/$(dir)/*.d))
	@mkdir -p $(@D)
	@$(PERL) mergedep.pl $@ $^

-include $(OBJDIR)/.deps

always:
	@:

.PHONY: all always \
	clean realclean distclean