Merge in Brian's massive build system cleanup effort.

Conflicts:
	.gitignore
	aos/build/build.sh
diff --git a/aos/atom_code/ipc_lib/aos_sync.c b/aos/atom_code/ipc_lib/aos_sync.c
index 1980a4d..18e65a7 100644
--- a/aos/atom_code/ipc_lib/aos_sync.c
+++ b/aos/atom_code/ipc_lib/aos_sync.c
@@ -10,7 +10,13 @@
 #include <string.h>
 #include <inttypes.h>
 
-#include "cmpxchg.h"
+// TODO(brians): Inline these in the new PI version.
+#define cmpxchg(ptr, o, n) __sync_val_compare_and_swap(ptr, o, n)
+static inline uint32_t xchg(mutex *pointer, uint32_t value) {
+  uint32_t result;
+  __atomic_exchange(pointer, &value, &result, __ATOMIC_SEQ_CST);
+  return result;
+}
 
 // this code is based on something that appears to be based on <http://www.akkadia.org/drepper/futex.pdf>, which also has a lot of useful information
 // should probably use <http://lxr.linux.no/linux+v2.6.34/Documentation/robust-futexes.txt> once it becomes available
diff --git a/aos/atom_code/ipc_lib/cmpxchg.h b/aos/atom_code/ipc_lib/cmpxchg.h
deleted file mode 100644
index 715c57d..0000000
--- a/aos/atom_code/ipc_lib/cmpxchg.h
+++ /dev/null
@@ -1,153 +0,0 @@
-#ifndef __ASM_CMPXCHG_H
-#define __ASM_CMPXCHG_H
-
-#include <stdint.h>
-
-//TODO implement xchg using gcc's atomic builtins (http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html)
-//or maybe http://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
-//__atomic_fetch_sub looks promising
-
-#define cmpxchg(ptr, o, n) __sync_val_compare_and_swap(ptr, o, n)
-/*#define xchg(ptr, n) ({typeof(*ptr) r; \
-    do{ \
-      r = *ptr; \
-    }while(!__sync_bool_compare_and_swap(ptr, r, n)); \
-    r; \
-})*/
-
-#  define LOCK "lock;"
-#  define LOCK_PREFIX "lock;"
-
-#define xchg(ptr,v) ((__typeof__(*(ptr)))__xchg((unsigned long)(v),(ptr),sizeof(*(ptr))))
-
-#define __xg(x) ((volatile long long *)(x))
-
-/*static inline void set_64bit(volatile unsigned long *ptr, unsigned long val)
-{
-  *ptr = val;
-}
-
-#define _set_64bit set_64bit*/
-
-/*
- * Note: no "lock" prefix even on SMP: xchg always implies lock anyway
- * Note 2: xchg has side effect, so that attribute volatile is necessary,
- *    but generally the primitive is invalid, *ptr is output argument. --ANK
- */
-static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
-{
-  switch (size) {
-    case 1:
-      __asm__ __volatile__("xchgb %b0,%1"
-          :"=q" (x)
-          :"m" (*__xg(ptr)), "0" (x)
-          :"memory");
-      break;
-    case 2:
-      __asm__ __volatile__("xchgw %w0,%1"
-          :"=r" (x)
-          :"m" (*__xg(ptr)), "0" (x)
-          :"memory");
-      break;
-    case 4:
-      __asm__ __volatile__("xchgl %k0,%1"
-          :"=r" (x)
-          :"m" (*__xg(ptr)), "0" (x)
-          :"memory");
-      break;
-    case 8:
-      __asm__ __volatile__("xchg %0,%1"
-          :"=r" (x)
-          :"m" (*__xg(ptr)), "0" (x)
-          :"memory");
-      break;
-  }
-  return x;
-}
-
-/*
- * Atomic compare and exchange.  Compare OLD with MEM, if identical,
- * store NEW in MEM.  Return the initial value in MEM.  Success is
- * indicated by comparing RETURN with OLD.
- */
-
-#if 0
-
-#define __HAVE_ARCH_CMPXCHG 1
-
-static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
-    unsigned long new, int size)
-{
-  int32_t prev;
-  switch (size) {
-    case 1:
-      __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
-            : "=a"(prev)
-            : "q"(new), "m"(*__xg(ptr)), "0"(old)
-            : "memory");
-      return prev;
-    case 2:
-      __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
-            : "=a"(prev)
-            : "r"(new), "m"(*__xg(ptr)), "0"(old)
-            : "memory");
-      return prev;
-    case 4:
-      __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %k1,%2"
-            : "=a"(prev)
-            : "r"(new), "m"(*__xg(ptr)), "0"(old)
-            : "memory");
-      return prev;
-    case 8:
-      __asm__ __volatile__("lock; cmpxchg %1,%2"
-            : "=a"(prev)
-            : "q"(new), "m"(*__xg(ptr)), "0"(old)
-            : "memory");
-      return prev;
-  }
-  return old;
-}
-
-/*
-static inline unsigned long __cmpxchg_local(volatile void *ptr,
-      unsigned long old, unsigned long new, int size)
-{
-  unsigned long prev;
-  switch (size) {
-  case 1:
-    __asm__ __volatile__("cmpxchgb %b1,%2"
-             : "=a"(prev)
-             : "q"(new), "m"(*__xg(ptr)), "0"(old)
-             : "memory");
-    return prev;
-  case 2:
-    __asm__ __volatile__("cmpxchgw %w1,%2"
-             : "=a"(prev)
-             : "r"(new), "m"(*__xg(ptr)), "0"(old)
-             : "memory");
-    return prev;
-  case 4:
-    __asm__ __volatile__("cmpxchgl %k1,%2"
-             : "=a"(prev)
-             : "r"(new), "m"(*__xg(ptr)), "0"(old)
-             : "memory");
-    return prev;
-  case 8:
-    __asm__ __volatile__("cmpxchgq %1,%2"
-             : "=a"(prev)
-             : "r"(new), "m"(*__xg(ptr)), "0"(old)
-             : "memory");
-    return prev;
-  }
-  return old;
-}*/
-
-#define cmpxchg(ptr,o,n)\
-  ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
-          (unsigned long)(n),sizeof(*(ptr))))
-/*#define cmpxchg_local(ptr,o,n)\
-  ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
-          (unsigned long)(n),sizeof(*(ptr))))*/
-#endif
-
-#endif
diff --git a/aos/build/aos.gypi b/aos/build/aos.gypi
index 9c74438..d8a4016 100644
--- a/aos/build/aos.gypi
+++ b/aos/build/aos.gypi
@@ -121,10 +121,10 @@
             '-mcpu=603e',
             '-mstrict-align',
             '-mlongcall',
-            '-isystem', '<(aos_abs)/externals/gccdist/WindRiver/gnu/3.4.4-vxworks-6.3/x86-win32/lib/gcc/powerpc-wrs-vxworks/3.4.4/include/',
-            '-isystem', '<(aos_abs)/externals/gccdist/WindRiver/vxworks-6.3/target/h/',
-            '-isystem', '<(aos_abs)/externals/gccdist/WindRiver/gnu/3.4.4-vxworks-6.3/x86-win32/include/c++/3.4.4/',
-            '-isystem', '<(aos_abs)/externals/gccdist/WindRiver/gnu/3.4.4-vxworks-6.3/x86-win32/include/c++/3.4.4/powerpc-wrs-vxworks/',
+            '-isystem', '<(aos_abs)/../output/downloaded/gccdist/WindRiver/gnu/3.4.4-vxworks-6.3/x86-win32/lib/gcc/powerpc-wrs-vxworks/3.4.4/include/',
+            '-isystem', '<(aos_abs)/../output/downloaded/gccdist/WindRiver/vxworks-6.3/target/h/',
+            '-isystem', '<(aos_abs)/../output/downloaded/gccdist/WindRiver/gnu/3.4.4-vxworks-6.3/x86-win32/include/c++/3.4.4/',
+            '-isystem', '<(aos_abs)/../output/downloaded/gccdist/WindRiver/gnu/3.4.4-vxworks-6.3/x86-win32/include/c++/3.4.4/powerpc-wrs-vxworks/',
             '-isystem', '<(WIND_BASE)/target/h',
             '-isystem', '<(WIND_BASE)/target/h/wrn/coreip',
           ],
diff --git a/aos/build/build.sh b/aos/build/build.sh
index e0ff434..c7a4bc4 100755
--- a/aos/build/build.sh
+++ b/aos/build/build.sh
@@ -21,37 +21,37 @@
 [ "${DEBUG}" == "yes" -o "${DEBUG}" == "no" ] || ( echo Debug "(${DEBUG})" must be '"yes" or "no"'. ; exit 1 )
 
 AOS=`dirname $0`/..
-NINJA_RELEASE=v1.4.0
-NINJA_DIR=${AOS}/externals/ninja-${NINJA_RELEASE}
-NINJA=${NINJA_DIR}/ninja
-# From chromium@154360:trunk/src/DEPS.
-GYP_REVISION=1738
-GYP_DIR=${AOS}/externals/gyp-${GYP_REVISION}
-GYP=${GYP_DIR}/gyp
 
-OUTDIR=${AOS}/../out_${OUT_NAME}
-BUILD_NINJA=${OUTDIR}/Default/build.ninja
+OUTDIR=${AOS}/../output/${OUT_NAME}
+BUILD_NINJA=${OUTDIR}/build.ninja
 
-[ -d ${NINJA_DIR} ] || git clone --branch ${NINJA_RELEASE} https://github.com/martine/ninja.git ${NINJA_DIR}
-[ -x ${NINJA} ] || ${NINJA_DIR}/bootstrap.py
-[ -d ${GYP_DIR} ] || ( svn co http://gyp.googlecode.com/svn/trunk -r ${GYP_REVISION} ${GYP_DIR} && patch -p1 -d ${GYP_DIR} < ${AOS}/externals/gyp.patch )
 ${AOS}/build/download_externals.sh
+. $(dirname $0)/tools_config
 
 # The exciting quoting is so that it ends up with -DWHATEVER='"'`a command`'"'.
 # The '"' at either end is so that it creates a string constant when expanded
 #   in the C/C++ code.
 COMMONFLAGS='-DLOG_SOURCENAME='"'\"'"'`basename $in`'"'\"' "
-if [ ${PLATFORM} == crio ]; then
-  COMMONFLAGS+='-DAOS_INITNAME=aos_init_function_`readlink -f $out | sed \"s/[\/.]/_/g\"` '
-fi
 
 if [[ "${ACTION}" != "clean" && ( ! -d ${OUTDIR} || -n \
   			"`find ${AOS}/.. -newer ${BUILD_NINJA} \( -name '*.gyp' -or -name '*.gypi' \)`" ) ]]; then
-  ${GYP} \
-    --check --depth=${AOS}/.. --no-circular-check -f ninja \
-    -I${AOS}/build/aos.gypi -Goutput_dir=out_${OUT_NAME} \
-    -DOS=${PLATFORM} -DWIND_BASE=${WIND_BASE} -DDEBUG=${DEBUG} \
-    ${GYP_MAIN}
+  # This is a gyp "file" that we pipe into gyp so that it will put the output
+  # in a directory named what we want where we want it.
+  GYP_INCLUDE=$(cat <<END
+{
+  'target_defaults': {
+    'configurations': {
+	  '${PLATFORM}': {}
+    }
+  }
+}
+END
+)
+  echo "${GYP_INCLUDE}" | ${GYP} \
+      --check --depth=${AOS}/.. --no-circular-check -f ninja \
+      -I${AOS}/build/aos.gypi -I/dev/stdin -Goutput_dir=output \
+      -DOS=${PLATFORM} -DWIND_BASE=${WIND_BASE} -DDEBUG=${DEBUG} \
+      ${GYP_MAIN}
   # Have to substitute "command = $compiler" so that it doesn't try to
   #   substitute them in the linker commands, where it doesn't work.
   sed -i "s:command = \$cc:\\0 ${COMMONFLAGS}:g ; \
@@ -70,28 +70,28 @@
   else
     NINJA_ACTION=
   fi
-  ${NINJA} -C ${OUTDIR}/Default ${NINJA_ACTION} "$@"
+  ${NINJA} -C ${OUTDIR} ${NINJA_ACTION} "$@"
   if [[ ${ACTION} == deploy || ${ACTION} == redeploy ]]; then
     [[ ${PLATFORM} =~ .*atom ]] && \
       rsync --progress -c -r \
-        ${OUTDIR}/Default/outputs/* \
+        ${OUTDIR}/outputs/* \
         driver@`${AOS}/build/get_ip fitpc`:/home/driver/robot_code/bin
 	  ssh driver@`${AOS}/build/get_ip fitpc` "sync; sync; sync"
     [ ${PLATFORM} == crio ] && \
       ncftpput `${AOS}/build/get_ip robot` / \
-      ${OUTDIR}/Default/lib/FRC_UserProgram.out
+      ${OUTDIR}/lib/FRC_UserProgram.out
   fi
   if [[ ${ACTION} == redeploy ]]; then
     if [[ ${PLATFORM} != crio ]]; then
       echo "Platform ${PLATFORM} does not support redeploy." 1>&2
       exit 1
     fi
-    ${OUTDIR}/../out_atom/Default/outputs/netconsole <<"END"
+    ${OUTDIR}/../out_atom/outputs/netconsole <<"END"
 unld "FRC_UserProgram.out"
 ld < FRC_UserProgram.out
 END
   fi
   if [[ ${ACTION} == tests ]]; then
-    find ${OUTDIR}/Default/tests -executable -exec {} \;
+    find ${OUTDIR}/tests -executable -exec {} \;
   fi
 fi
diff --git a/aos/build/download_externals.sh b/aos/build/download_externals.sh
index 13c8eff..be77aa5 100755
--- a/aos/build/download_externals.sh
+++ b/aos/build/download_externals.sh
@@ -2,8 +2,19 @@
 
 set -e
 
-AOS=`dirname $0`/..
-EXTERNALS=${AOS}/externals
+AOS=$(readlink -f $(dirname $0)/..)
+. $(dirname $0)/tools_config
+
+TMPDIR=/tmp/$$-aos-tmpdir
+mkdir -p ${EXTERNALS}
+mkdir -p ${COMPILED}
+
+# get and build ninja
+[ -d ${NINJA_DIR} ] || git clone --branch ${NINJA_RELEASE} https://github.com/martine/ninja.git ${NINJA_DIR}
+[ -x ${NINJA} ] || ${NINJA_DIR}/bootstrap.py
+
+# get gyp
+[ -d ${GYP_DIR} ] || ( svn co http://gyp.googlecode.com/svn/trunk -r ${GYP_REVISION} ${GYP_DIR} && patch -p1 -d ${GYP_DIR} < ${AOS}/externals/gyp.patch )
 
 # get gccdist
 GCCDIST=${EXTERNALS}/gccdist
@@ -32,7 +43,7 @@
 LIBJPEG_VERSION=8d
 LIBJPEG_DIR=${EXTERNALS}/jpeg-${LIBJPEG_VERSION}
 # NOTE: this directory ends up in #include names
-LIBJPEG_PREFIX=${EXTERNALS}/libjpeg
+LIBJPEG_PREFIX=${COMPILED}/libjpeg
 LIBJPEG_LIB=${LIBJPEG_PREFIX}/lib/libjpeg.a
 LIBJPEG_TAR=${EXTERNALS}/jpegsrc.v${LIBJPEG_VERSION}.tar.gz
 [ -f ${LIBJPEG_TAR} ] || wget http://www.ijg.org/files/jpegsrc.v${LIBJPEG_VERSION}.tar.gz -O ${LIBJPEG_TAR}
@@ -41,26 +52,26 @@
 
 # get gtest
 GTEST_VERSION=1.6.0
-GTEST_DIR=${EXTERNALS}/gtest-${GTEST_VERSION}-p1
+GTEST_DIR=${EXTERNALS}/gtest-${GTEST_VERSION}
 GTEST_ZIP=${EXTERNALS}/gtest-${GTEST_VERSION}.zip
-TMPDIR=/tmp/$$-aos-tmpdir
 [ -f ${GTEST_ZIP} ] || wget http://googletest.googlecode.com/files/gtest-${GTEST_VERSION}.zip -O ${GTEST_ZIP}
-[ -d ${GTEST_DIR} ] || ( unzip ${GTEST_ZIP} -d ${TMPDIR} && mv ${TMPDIR}/gtest-${GTEST_VERSION} ${GTEST_DIR} && cd ${GTEST_DIR} && patch -p1 < ../gtest.patch )
+[ -d ${GTEST_DIR} ] || ( unzip ${GTEST_ZIP} -d ${TMPDIR} && mv ${TMPDIR}/gtest-${GTEST_VERSION} ${GTEST_DIR} && cd ${GTEST_DIR} && patch -p1 < ${AOS}/externals/gtest.patch )
 
 # get and build ctemplate
 # This is the next revision after the 2.2 release and it only adds spaces to
 # make gcc 4.7 with --std=c++11 happy (user-defined string literals...).
 CTEMPLATE_VERSION=129
-CTEMPLATE_DIR=${EXTERNALS}/ctemplate-${CTEMPLATE_VERSION}
+CTEMPLATE_TAR=${EXTERNALS}/ctemplate-${CTEMPLATE_VERSION}.tar.gz
+CTEMPLATE_DIR=${COMPILED}/ctemplate-${CTEMPLATE_VERSION}
 CTEMPLATE_PREFIX=${CTEMPLATE_DIR}-prefix
 CTEMPLATE_LIB=${CTEMPLATE_PREFIX}/lib/libctemplate.a
 CTEMPLATE_URL=http://ctemplate.googlecode.com
 if [[ "${CTEMPLATE_VERSION}" =~ /\./ ]]; then
 	CTEMPLATE_URL=${CTEMPLATE_URL}/files/ctemplate-${CTEMPLATE_VERSION}.tar.gz
-	[ -f ${CTEMPLATE_DIR}.tar.gz ] || \
-		wget ${CTEMPLATE_URL} -O ${CTEMPLATE_DIR}.tar.gz
+	[ -f ${CTEMPLATE_TAR} ] || \
+		wget ${CTEMPLATE_URL} -O ${CTEMPLATE_TAR}
 	[ -d ${CTEMPLATE_DIR} ] || ( mkdir ${CTEMPLATE_DIR} && tar \
-		--strip-components=1 -C ${CTEMPLATE_DIR} -xf ${CTEMPLATE_DIR}.tar.gz )
+		--strip-components=1 -C ${CTEMPLATE_DIR} -xf ${CTEMPLATE_TAR} )
 else
 	CTEMPLATE_URL=${CTEMPLATE_URL}/svn/trunk
 	[ -d ${CTEMPLATE_DIR} ] || \
@@ -73,13 +84,14 @@
 
 # get and build gflags
 GFLAGS_VERSION=2.0
-GFLAGS_DIR=${EXTERNALS}/gflags-${GFLAGS_VERSION}
+GFLAGS_TAR=${EXTERNALS}/gflags-${GFLAGS_VERSION}.tar.gz
+GFLAGS_DIR=${COMPILED}/gflags-${GFLAGS_VERSION}
 GFLAGS_PREFIX=${GFLAGS_DIR}-prefix
 GFLAGS_LIB=${GFLAGS_PREFIX}/lib/libgflags.a
 GFLAGS_URL=https://gflags.googlecode.com/files/gflags-${GFLAGS_VERSION}.tar.gz
-[ -f ${GFLAGS_DIR}.tar.gz ] || wget ${GFLAGS_URL} -O ${GFLAGS_DIR}.tar.gz
+[ -f ${GFLAGS_TAR} ] || wget ${GFLAGS_URL} -O ${GFLAGS_TAR}
 [ -d ${GFLAGS_DIR} ] || ( mkdir ${GFLAGS_DIR} && tar \
-  --strip-components=1 -C ${GFLAGS_DIR} -xf ${GFLAGS_DIR}.tar.gz )
+  --strip-components=1 -C ${GFLAGS_DIR} -xf ${GFLAGS_TAR} )
 [ -f ${GFLAGS_LIB} ] || env -i PATH="${PATH}" \
   CFLAGS='-m32' CXXFLAGS='-m32' LDFLAGS='-m32' \
   bash -c "cd ${GFLAGS_DIR} && ./configure \
@@ -88,13 +100,14 @@
 # get and build libusb
 LIBUSB_VERSION=1.0.9
 LIBUSB_APIVERSION=1.0
-LIBUSB_DIR=${EXTERNALS}/libusb-${LIBUSB_VERSION}
+LIBUSB_TAR=${EXTERNALS}/libusb-${LIBUSB_VERSION}.tar.bz2
+LIBUSB_DIR=${COMPILED}/libusb-${LIBUSB_VERSION}
 LIBUSB_PREFIX=${LIBUSB_DIR}-prefix
 LIBUSB_LIB=${LIBUSB_PREFIX}/lib/libusb-${LIBUSB_APIVERSION}.a
 LIBUSB_URL=http://sourceforge.net/projects/libusb/files/libusb-${LIBUSB_APIVERSION}/libusb-${LIBUSB_VERSION}/libusb-${LIBUSB_VERSION}.tar.bz2
-[ -f ${LIBUSB_DIR}.tar.bz2 ] || wget ${LIBUSB_URL} -O ${LIBUSB_DIR}.tar.bz2
+[ -f ${LIBUSB_TAR} ] || wget ${LIBUSB_URL} -O ${LIBUSB_TAR}
 [ -d ${LIBUSB_DIR} ] || ( mkdir ${LIBUSB_DIR} && tar \
-  --strip-components=1 -C ${LIBUSB_DIR} -xf ${LIBUSB_DIR}.tar.bz2 )
+  --strip-components=1 -C ${LIBUSB_DIR} -xf ${LIBUSB_TAR} )
 [ -f ${LIBUSB_LIB} ] || env -i PATH="${PATH}" \
   CFLAGS='-m32' CXXFLAGS='-m32' LDFLAGS='-m32' \
   bash -c "cd ${LIBUSB_DIR} && ./configure \
@@ -109,14 +122,15 @@
 
 # get and build libevent
 LIBEVENT_VERSION=2.0.21
-LIBEVENT_DIR=${EXTERNALS}/libevent-${LIBEVENT_VERSION}
+LIBEVENT_TAR=${EXTERNALS}/libevent-${LIBEVENT_VERSION}.tar.gz
+LIBEVENT_DIR=${COMPILED}/libevent-${LIBEVENT_VERSION}
 LIBEVENT_PREFIX=${LIBEVENT_DIR}-prefix
 LIBEVENT_LIB=${LIBEVENT_PREFIX}/lib/libevent.a
 LIBEVENT_URL=https://github.com/downloads/libevent/libevent
 LIBEVENT_URL=${LIBEVENT_URL}/libevent-${LIBEVENT_VERSION}-stable.tar.gz
-[ -f ${LIBEVENT_DIR}.tar.gz ] || wget ${LIBEVENT_URL} -O ${LIBEVENT_DIR}.tar.gz
+[ -f ${LIBEVENT_TAR} ] || wget ${LIBEVENT_URL} -O ${LIBEVENT_TAR}
 [ -d ${LIBEVENT_DIR} ] || ( mkdir ${LIBEVENT_DIR} && tar \
-  --strip-components=1 -C ${LIBEVENT_DIR} -xf ${LIBEVENT_DIR}.tar.gz )
+  --strip-components=1 -C ${LIBEVENT_DIR} -xf ${LIBEVENT_TAR} )
 [ -f ${LIBEVENT_LIB} ] || env -i PATH="${PATH}" \
   CFLAGS='-m32' CXXFLAGS='-m32' LDFLAGS='-m32' \
   bash -c "cd ${LIBEVENT_DIR} && ./configure \
@@ -124,15 +138,18 @@
 
 # get and build libcdd
 LIBCDD_VERSION=094g
-LIBCDD_DIR=${EXTERNALS}/libcdd-${LIBCDD_VERSION}
+LIBCDD_TAR=${EXTERNALS}/libcdd-${LIBCDD_VERSION}.tar.gz
+LIBCDD_DIR=${COMPILED}/libcdd-${LIBCDD_VERSION}
 LIBCDD_PREFIX=${LIBCDD_DIR}-prefix
 LIBCDD_LIB=${LIBCDD_PREFIX}/lib/libcdd.a
 LIBCDD_URL=ftp://ftp.ifor.math.ethz.ch/pub/fukuda/cdd/cddlib-${LIBCDD_VERSION}.tar.gz
-[ -f ${LIBCDD_DIR}.tar.gz ] || \
-        wget ${LIBCDD_URL} -O ${LIBCDD_DIR}.tar.gz
+[ -f ${LIBCDD_TAR} ] || \
+        wget ${LIBCDD_URL} -O ${LIBCDD_TAR}
 [ -d ${LIBCDD_DIR} ] || ( mkdir ${LIBCDD_DIR} && tar \
-        --strip-components=1 -C ${LIBCDD_DIR} -xf ${LIBCDD_DIR}.tar.gz )
+        --strip-components=1 -C ${LIBCDD_DIR} -xf ${LIBCDD_TAR} )
 [ -f ${LIBCDD_LIB} ] || env -i PATH="${PATH}" \
         CFLAGS='-m32' CXXFLAGS='-m32' LDFLAGS='-m32' \
         bash -c "cd ${LIBCDD_DIR} && ./configure --disable-shared \
         --prefix=`readlink -f ${LIBCDD_PREFIX}` && make && make install"
+
+rm -rf ${TMPDIR}
diff --git a/aos/build/externals.gyp b/aos/build/externals.gyp
index 99b26cf..283e7ce 100644
--- a/aos/build/externals.gyp
+++ b/aos/build/externals.gyp
@@ -2,12 +2,14 @@
 # download_externals.sh makes sure that all of them have been downloaded.
 {
   'variables': {
-    'externals': '<(AOS)/externals',
-    'externals_abs': '<!(readlink -f ../externals)',
+    'externals': '<(AOS)/../output/downloaded',
+    'externals_abs': '<!(readlink -f ../../output/downloaded)',
+    'compiled': '<(externals)/../compiled-i386',
+    'compiled_abs': '<(externals_abs)/../compiled-i386',
 
 # These versions have to be kept in sync with the ones in download_externals.sh.
     'eigen_version': '3.1.3',
-    'gtest_version': '1.6.0-p1',
+    'gtest_version': '1.6.0',
     'onejar_version': '0.97',
     'ctemplate_version': '129',
     'gflags_version': '2.0',
@@ -22,7 +24,7 @@
       'target_name': 'WPILib',
       'type': 'static_library',
       'sources': [
-        '<!@(find <(externals)/WPILib/WPILib/ -name *.cpp)',
+        '<!@(find <(AOS)/externals/WPILib/WPILib/ -name *.cpp)',
       ],
       'cflags!': [
         '-Werror',
@@ -34,13 +36,13 @@
         '-O3'
       ],
       'include_dirs': [
-        '<(externals)/WPILib',
-        '<(externals)/WPILib/WPILib',
+        '<(AOS)/externals/WPILib',
+        '<(AOS)/externals/WPILib/WPILib',
       ],
       'direct_dependent_settings': {
         'cflags': [
-          '-isystem', '<(externals_abs)/WPILib',
-          '-isystem', '<(externals_abs)/WPILib/WPILib',
+          '-isystem', '<(AOS)/externals/WPILib',
+          '-isystem', '<(AOS)/externals/WPILib/WPILib',
         ],
       },
     },
@@ -48,14 +50,14 @@
       'target_name': 'WPILib-NetworkRobotValues',
       'type': 'static_library',
       'sources': [
-        '<(externals)/WPILib/WPILib/NetworkRobot/NetworkRobotValues.cpp'
+        '<(AOS)/externals/WPILib/WPILib/NetworkRobot/NetworkRobotValues.cpp'
       ],
       'include_dirs': [
-        '<(externals)/WPILib',
+        '<(AOS)/externals/WPILib',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
-          '<(externals)/WPILib',
+          '<(AOS)/externals/WPILib',
         ],
       },
     },
@@ -102,10 +104,10 @@
       'target_name': 'libevent',
       'type': 'none',
       'link_settings': {
-        'libraries': ['<(externals_abs)/libevent-<(libevent_version)-prefix/lib/libevent.a'],
+        'libraries': ['<(compiled_abs)/libevent-<(libevent_version)-prefix/lib/libevent.a'],
       },
       'direct_dependent_settings': {
-        'include_dirs': ['<(externals)/libevent-<(libevent_version)-prefix/include'],
+        'include_dirs': ['<(compiled)/libevent-<(libevent_version)-prefix/include'],
       },
     },
     {
@@ -121,7 +123,10 @@
       'target_name': 'libjpeg',
       'type': 'none',
       'direct_dependent_settings': {
-        'libraries': ['<(externals_abs)/libjpeg/lib/libjpeg.a'],
+        'libraries': ['<(compiled_abs)/libjpeg/lib/libjpeg.a'],
+        'cflags': [
+          '-isystem', '<(compiled)',
+        ],
       },
     },
     {
@@ -182,40 +187,40 @@
       'target_name': 'ctemplate',
       'type': 'none',
       'link_settings': {
-        'libraries': ['<(externals_abs)/ctemplate-<(ctemplate_version)-prefix/lib/libctemplate.a'],
+        'libraries': ['<(compiled_abs)/ctemplate-<(ctemplate_version)-prefix/lib/libctemplate.a'],
       },
       'direct_dependent_settings': {
-        'include_dirs': ['<(externals)/ctemplate-<(ctemplate_version)-prefix/include'],
+        'include_dirs': ['<(compiled)/ctemplate-<(ctemplate_version)-prefix/include'],
       },
     },
     {
       'target_name': 'gflags',
       'type': 'none',
       'link_settings': {
-        'libraries': ['<(externals_abs)/gflags-<(gflags_version)-prefix/lib/libgflags.a'],
+        'libraries': ['<(compiled_abs)/gflags-<(gflags_version)-prefix/lib/libgflags.a'],
       },
       'direct_dependent_settings': {
-        'include_dirs': ['<(externals)/gflags-<(gflags_version)-prefix/include'],
+        'include_dirs': ['<(compiled)/gflags-<(gflags_version)-prefix/include'],
       },
     },
     {
       'target_name': 'libusb',
       'type': 'none',
       'link_settings': {
-        'libraries': ['<(externals_abs)/libusb-<(libusb_version)-prefix/lib/libusb-<(libusb_apiversion).a'],
+        'libraries': ['<(compiled_abs)/libusb-<(libusb_version)-prefix/lib/libusb-<(libusb_apiversion).a'],
       },
       'direct_dependent_settings': {
-        'include_dirs': ['<(externals)/libusb-<(libusb_version)-prefix/include'],
+        'include_dirs': ['<(compiled)/libusb-<(libusb_version)-prefix/include'],
       },
     },
     {
       'target_name': 'libcdd',
       'type': 'none',
       'link_settings': {
-        'libraries': ['<(externals_abs)/libcdd-<(libcdd_version)-prefix/lib/libcdd.a'],
+        'libraries': ['<(compiled_abs)/libcdd-<(libcdd_version)-prefix/lib/libcdd.a'],
       },
       'direct_dependent_settings': {
-        'include_dirs': ['<(externals_abs)/libcdd-<(libcdd_version)-prefix/include'],
+        'include_dirs': ['<(compiled_abs)/'],
       },
     },
   ],
diff --git a/aos/build/tools_config b/aos/build/tools_config
new file mode 100644
index 0000000..653c1ef
--- /dev/null
+++ b/aos/build/tools_config
@@ -0,0 +1,14 @@
+# This is a shell fragment that sets up variables related to where the tools
+# that download_externals.sh downloads so build.sh can use.
+
+EXTERNALS=${AOS}/../output/downloaded
+COMPILED=${EXTERNALS}/../compiled-i386
+
+NINJA_RELEASE=v1.4.0
+NINJA_DIR=${EXTERNALS}/ninja-${NINJA_RELEASE}
+NINJA=${NINJA_DIR}/ninja
+
+# From chromium@154360:trunk/src/DEPS.
+GYP_REVISION=1738
+GYP_DIR=${EXTERNALS}/gyp-${GYP_REVISION}
+GYP=${GYP_DIR}/gyp
diff --git a/aos/controls/polytope.h b/aos/controls/polytope.h
index ed4b36d..a873722 100644
--- a/aos/controls/polytope.h
+++ b/aos/controls/polytope.h
@@ -2,8 +2,8 @@
 #define _AOS_CONTROLS_POLYTOPE_H_
 
 #include "Eigen/Dense"
-#include "aos/externals/libcdd-094g-prefix/include/setoper.h"
-#include "aos/externals/libcdd-094g-prefix/include/cdd.h"
+#include "libcdd-094g-prefix/include/setoper.h"
+#include "libcdd-094g-prefix/include/cdd.h"
 
 namespace aos {
 namespace controls {
diff --git a/aos/externals/.gitignore b/aos/externals/.gitignore
deleted file mode 100644
index 694129e..0000000
--- a/aos/externals/.gitignore
+++ /dev/null
@@ -1,31 +0,0 @@
-/ctemplate-129-prefix/
-/ctemplate-129.tar.gz
-/ctemplate-129/
-/eigen-3.1.3.tar.bz2
-/eigen-3.1.3/
-/gccdist.zip
-/gccdist/
-/gtest-1.6.0-p1/
-/gtest-1.6.0.zip
-/gyp-1738/
-/javacv-0.2-bin.zip
-/javacv-bin/
-/jpeg-8d/
-/jpegsrc.v8d.tar.gz
-/libjpeg/
-/ninja-v1.4.0/
-/one-jar-boot-0.97.jar
-/gflags-2.0-prefix/
-/gflags-2.0.tar.gz
-/gflags-2.0/
-/libusb-1.0.9-prefix/
-/libusb-1.0.9.tar.bz2
-/libusb-1.0.9/
-/compiler-rt-RELEASE_32_final/
-/libevent-2.0.21-prefix/
-/libevent-2.0.21.tar.gz
-/libevent-2.0.21/
-/libcdd-094g-prefix/
-/libcdd-094g.tar.gz
-/libcdd-094g/
-