Problem set 1 for 2019.

.gitignore

@@ -0,0 +1,26 @@
+#*#
+*.aux
+*.backup
+*.core
+*.dSYM
+*.dvi
+*.gcda
+*.log
+*.noopt
+*.o
+*.optimized
+*.unsafe
+*~
+.DS_Store
+.cproject
+.deps
+.gitcheckout
+.goutputstream-*
+.project
+a.out
+core*
+strace.out
+tags
+tags.*
+typescript
+vgcore*

README.md

@@ -0,0 +1,8 @@
+CS 61 Problem Sets
+==================
+
+This repository contains the problem sets for Harvard’s CS 61 class, Systems
+Programming and Machine Organization.
+
+For more information, see the course wiki:
+https://cs61.seas.harvard.edu/

pset1/.gitignore

@@ -0,0 +1,6 @@
+*.dSYM
+*.o
+.deps
+hhtest
+out
+test[0-9][0-9][0-9]

pset1/AUTHORS.md

@@ -0,0 +1,17 @@
+Author and collaborators
+========================
+
+Primary student
+---------------
+(Your name.)
+
+
+Collaborators
+-------------
+(List any other collaborators and describe help you got from other students
+in the class.)
+
+
+Citations
+---------
+(List any other sources consulted.)

pset1/GNUmakefile

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+# Default optimization level
+O ?= 2
+
+TESTS = $(patsubst %.cc,%,$(sort $(wildcard test[0-9][0-9][0-9].cc)))
+
+all: $(TESTS) hhtest
+
+-include build/rules.mk
+
+LIBS = -lm
+
+%.o: %.cc $(BUILDSTAMP)
+	$(call run,$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPCFLAGS) $(O) -o $@ -c,COMPILE,$<)
+
+all:
+	@echo "*** Run 'make check' or 'make check-all' to check your work."
+
+test%: m61.o basealloc.o test%.o
+	$(call run,$(CXX) $(CXXFLAGS) $(O) -o $@ $^ $(LDFLAGS) $(LIBS),LINK $@)
+
+hhtest: m61.o basealloc.o hhtest.o
+	$(call run,$(CXX) $(CXXFLAGS) $(O) -o $@ $^ $(LDFLAGS) $(LIBS),LINK $@)
+
+check: $(patsubst %,run-%,$(TESTS))
+	@echo "*** All tests succeeded!"
+
+check-all: $(TESTS)
+	@good=true; for i in $(TESTS); do $(MAKE) --no-print-directory run-$$i || good=false; done; \
+	if $$good; then echo "*** All tests succeeded!"; fi; $$good
+
+check-%:
+	@any=false; good=true; for i in `perl check.pl -e "$*"`; do \
+	    any=true; $(MAKE) run-$$i || good=false; done; \
+	if $$any; then $$good; else echo "*** No such test" 1>&2; $$any; fi
+
+run-:
+	@echo "*** No such test" 1>&2; exit 1
+
+run-%: %
+	@test -d out || mkdir out
+	@perl check.pl -x $<
+
+clean: clean-main
+clean-main:
+	$(call run,rm -f $(TESTS) hhtest *.o core *.core,CLEAN)
+	$(call run,rm -rf out *.dSYM $(DEPSDIR))
+
+distclean: clean
+
+MALLOC_CHECK_=0
+export MALLOC_CHECK_
+
+.PRECIOUS: %.o
+.PHONY: all clean clean-main clean-hook distclean \
+	run run- run% prepare-check check check-all check-%

pset1/README.md

@@ -0,0 +1,14 @@
+CS 61 Problem Set 1
+===================
+
+**Fill out both this file and `AUTHORS.md` before submitting.** We grade
+anonymously, so put all personally identifying information, including
+collaborators, in `AUTHORS.md`.
+
+Grading notes (if any)
+----------------------
+
+
+
+Extra credit attempted (if any)
+-------------------------------

pset1/basealloc.cc

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+#define M61_DISABLE 1
+#include "m61.hh"
+#include <unordered_map>
+#include <vector>
+#include <sys/mman.h>
+
+
+// This file contains a base memory allocator guaranteed not to
+// overwrite freed allocations. No need to understand it.
+
+
+using base_allocation = std::pair<uintptr_t, size_t>;
+
+// `allocs` is a hash table mapping active pointer address to allocation size.
+// `frees` is a vector of freed allocations.
+static std::unordered_map<uintptr_t, size_t> allocs;
+static std::vector<base_allocation> frees;
+static int disabled;
+
+static unsigned alloc_random() {
+    static uint64_t x = 8973443640547502487ULL;
+    x = x * 6364136223846793005ULL + 1ULL;
+    return x >> 32;
+}
+
+static void base_allocator_atexit();
+
+void* base_malloc(size_t sz) {
+    if (disabled) {
+        return malloc(sz);
+    }
+    ++disabled;
+    uintptr_t ptr = 0;
+
+    static int base_alloc_atexit_installed = 0;
+    if (!base_alloc_atexit_installed) {
+        atexit(base_allocator_atexit);
+        base_alloc_atexit_installed = 1;
+    }
+
+    // try to use a previously-freed block 75% of the time
+    unsigned r = alloc_random();
+    if (r % 4 != 0) {
+        for (unsigned ntries = 0; ntries < 10 && ntries < frees.size(); ++ntries) {
+            auto& f = frees[alloc_random() % frees.size()];
+            if (f.second >= sz) {
+                allocs.insert(f);
+                ptr = f.first;
+                f = frees.back();
+                frees.pop_back();
+                break;
+            }
+        }
+    }
+
+    if (!ptr) {
+        // need a new allocation
+        ptr = reinterpret_cast<uintptr_t>(malloc(sz ? sz : 1));
+    }
+    if (ptr) {
+        allocs[reinterpret_cast<uintptr_t>(ptr)] = sz;
+    }
+
+    --disabled;
+    return reinterpret_cast<void*>(ptr);
+}
+
+void base_free(void* ptr) {
+    if (disabled || !ptr) {
+        free(ptr);
+    } else {
+        // mark free if found; if not found, invalid free: silently ignore
+        ++disabled;
+        auto it = allocs.find(reinterpret_cast<uintptr_t>(ptr));
+        if (it != allocs.end()) {
+            frees.push_back(*it);
+            allocs.erase(it);
+        }
+        --disabled;
+    }
+}
+
+void base_allocator_disable(bool d) {
+    disabled = d;
+}
+
+static void base_allocator_atexit() {
+    // clean up freed memory to shut up leak detector
+    for (auto& alloc : frees) {
+        free(reinterpret_cast<void*>(alloc.first));
+    }
+}

pset1/build/rules.mk

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+# are we using clang?
+ISCLANG := $(shell if $(CC) --version | grep -e 'LLVM\|clang' >/dev/null; then echo 1; fi)
+ISLINUX := $(if $(wildcard /usr/include/linux/*.h),1,)
+
+CFLAGS := -std=gnu11 -W -Wall -Wshadow -Wno-unused-command-line-argument -g $(DEFS) $(CFLAGS)
+CXXFLAGS := -std=gnu++1z -W -Wall -Wshadow  -Wno-unused-command-line-argument -g $(DEFS) $(CXXFLAGS)
+O ?= -O3
+ifeq ($(filter 0 1 2 3 s,$(O)$(NOOVERRIDEO)),$(strip $(O)))
+override O := -O$(O)
+endif
+LDFLAGS := -no-pie
+
+# sanitizer arguments
+ifndef SAN
+SAN := $(SANITIZE)
+endif
+ifndef TSAN
+ ifeq ($(WANT_TSAN),1)
+TSAN := $(SAN)
+ endif
+endif
+
+check_for_sanitizer = $(if $(strip $(shell $(CC) -fsanitize=$(1) -x c -E /dev/null 2>&1 | grep sanitize=)),$(info ** WARNING: The `$(CC)` compiler does not support `-fsanitize=$(1)`.),1)
+ifeq ($(TSAN),1)
+ ifeq ($(or $(ISCLANG),$(filter-out 3.% 4.% 5.% 6.%,$(shell $(CC) -dumpversion)),$(filter-out Linux%,$(shell uname))),)
+$(info ** WARNING: If ThreadSanitizer fails, try `make SAN=1 CC=clang`.)
+ endif
+ ifeq ($(call check_for_sanitizer,thread),1)
+CFLAGS += -fsanitize=thread
+CXXFLAGS += -fsanitize=thread
+ endif
+else
+ ifeq ($(or $(ASAN),$(SAN)),1)
+  ifeq ($(call check_for_sanitizer,address),1)
+CFLAGS += -fsanitize=address
+CXXFLAGS += -fsanitize=address
+  endif
+ endif
+ ifeq ($(or $(LSAN),$(LEAKSAN)),1)
+  ifeq ($(call check_for_sanitizer,leak),1)
+CFLAGS += -fsanitize=leak
+CXXFLAGS += -fsanitize=leak
+  endif
+ endif
+endif
+ifeq ($(or $(UBSAN),$(SAN)),1)
+ ifeq ($(call check_for_sanitizer,undefined),1)
+CFLAGS += -fsanitize=undefined
+CXXFLAGS += -fsanitize=undefined
+ endif
+endif
+
+# profiling
+ifeq ($(or $(PROFILE),$(PG)),1)
+CFLAGS += -pg
+CXXFLAGS += -pg
+endif
+
+# these rules ensure dependencies are created
+DEPCFLAGS = -MD -MF $(DEPSDIR)/$*.d -MP
+DEPSDIR := .deps
+BUILDSTAMP := $(DEPSDIR)/rebuildstamp
+DEPFILES := $(wildcard $(DEPSDIR)/*.d)
+ifneq ($(DEPFILES),)
+include $(DEPFILES)
+endif
+
+# when the C compiler or optimization flags change, rebuild all objects
+ifneq ($(strip $(DEP_CC)),$(strip $(CC) $(CPPFLAGS) $(CFLAGS) $(O)))
+DEP_CC := $(shell mkdir -p $(DEPSDIR); echo >$(BUILDSTAMP); echo "DEP_CC:=$(CC) $(CPPFLAGS) $(CFLAGS) $(O)" >$(DEPSDIR)/_cc.d)
+endif
+ifneq ($(strip $(DEP_CXX)),$(strip $(CXX) $(CPPFLAGS) $(CXXFLAGS) $(O)))
+DEP_CXX := $(shell mkdir -p $(DEPSDIR); echo >$(BUILDSTAMP); echo "DEP_CXX:=$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(O)" >$(DEPSDIR)/_cxx.d)
+endif
+
+
+V = 0
+ifeq ($(V),1)
+run = $(1) $(3)
+xrun = /bin/echo "$(1) $(3)" && $(1) $(3)
+else
+run = @$(if $(2),/bin/echo "  $(2) $(3)" &&,) $(1) $(3)
+xrun = $(if $(2),/bin/echo "  $(2) $(3)" &&,) $(1) $(3)
+endif
+runquiet = @$(1) $(3)
+
+# cancel implicit rules we don't want
+%: %.c
+%.o: %.c
+%: %.cc
+%.o: %.cc
+%: %.o
+
+$(BUILDSTAMP):
+	@mkdir -p $(@D)
+	@echo >$@
+
+always:
+	@:
+
+clean-hook:
+	@:
+
+.PHONY: always clean-hook
+.PRECIOUS: %.o