From 6d85de341928aef8178465c60122f3cbe76f5dd6 Mon Sep 17 00:00:00 2001
From: Thomas Martitz <kugel@rockbox.org>
Date: Fri, 18 Feb 2011 22:46:01 +0000
Subject: Implement cooperative threads on hosted platforms using C code.

This replaces SDL threads with real cooperative threads, which are less cpu intensive and allow priority scheduling.
The backend for context switching is dependant on the host (sigaltstack/longjmp on Unix, Fibers on Windows).
configure has options to force or disallow SDL threads.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29327 a1c6a512-1295-4272-9138-f99709370657
---
 tools/configure | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 77 insertions(+), 1 deletion(-)

(limited to 'tools')

diff --git a/tools/configure b/tools/configure
index bcb7d0a864..889012ab78 100755
--- a/tools/configure
+++ b/tools/configure
@@ -25,6 +25,7 @@ bindir=
 libdir=
 sharedir=
 
+thread_support="ASSEMBLER_THREADS"
 app_modelname=
 app_lcd_width=
 app_lcd_height=
@@ -163,6 +164,39 @@ findsdl(){
   done
 }
 
+# check for availability of sigaltstack to support our thread engine
+check_sigaltstack() {
+   cat >$tmpdir/check_threads.c <<EOF
+#include <signal.h>
+int main(int argc, char **argv)
+{
+  #define NULL (void*)0
+  sigaltstack(NULL, NULL);
+  return 0;
+}
+EOF
+   $CC -o $tmpdir/check_threads $tmpdir/check_threads.c 1> /dev/null
+   result=$?
+   rm -rf $tmpdir/check_threads*
+   echo $result
+}
+
+# check for availability of Fiber on Win32 to support our thread engine
+check_fiber() {
+   cat >$tmpdir/check_threads.c <<EOF
+#include <windows.h>
+int main(int argc, char **argv)
+{
+  ConvertThreadToFiber(NULL);
+  return 0;
+}
+EOF
+   $CC -o $tmpdir/check_threads $tmpdir/check_threads.c 2>/dev/null
+   result=$?
+   rm -rf $tmpdir/check_threads*
+   echo $result
+}
+
 simcc () {
 
  # default tool setup for native building
@@ -175,6 +209,8 @@ simcc () {
  GCCOPTS="$GCCOPTS -fno-builtin -g"
  GCCOPTIMIZE=''
  LDOPTS='-lm' # button-sdl.c uses sqrt()
+ sigaltstack=""
+ fibers=""
 
  # default output binary name, don't override app_get_platform()
  if [ "$app_type" != "sdl-app" ]; then
@@ -193,6 +229,7 @@ simcc () {
    CYGWIN*)
    echo "Cygwin host detected"
 
+   fibers=`check_fiber`
    LDOPTS="$LDOPTS -mconsole"
    output="$output.exe"
    winbuild="yes"
@@ -201,29 +238,33 @@ simcc () {
    MINGW*)
    echo "MinGW host detected"
 
+   fibers=`check_fiber`
    LDOPTS="$LDOPTS -mconsole"
    output="$output.exe"
    winbuild="yes"
    ;;
 
    Linux)
+   sigaltstack=`check_sigaltstack`
    echo "Linux host detected"
    LDOPTS="$LDOPTS -ldl"
    ;;
 
    FreeBSD)
+   sigaltstack=`check_sigaltstack`
    echo "FreeBSD host detected"
    LDOPTS="$LDOPTS -ldl"
    ;;
 
    Darwin)
+   sigaltstack=`check_sigaltstack`
    echo "Darwin host detected"
    LDOPTS="$LDOPTS -ldl"
-
    SHARED_FLAG="-dynamiclib -Wl\,-single_module"
    ;;
 
    SunOS)
+   sigaltstack=`check_sigaltstack`
    echo "*Solaris host detected"
 
    GCCOPTS="$GCCOPTS -fPIC"
@@ -319,11 +360,33 @@ EOF
    # add cross-compiler option(s)
    prefixtools i586-mingw32msvc-
    LDOPTS="$LDOPTS -mconsole"
+   fibers=`check_fiber`
    output="rockboxui.exe"
    endian="little" # windows is little endian
    echo "Enabling MMX support"
    GCCOPTS="$GCCOPTS -mmmx"
  fi
+
+ thread_support=
+ if [ -z "$ARG_THREAD_SUPPORT" ] || [ "$ARG_THREAD_SUPPORT" = "0" ]; then
+   if [ "$sigaltstack" = "0" ]; then
+     thread_support="HAVE_SIGALTSTACK_THREADS"
+     echo "Selected sigaltstack threads"
+   elif [ "$fibers" = "0" ]; then
+     thread_support="HAVE_WIN32_FIBER_THREADS"
+     echo "Selected Win32 Fiber threads"
+   fi
+ fi
+
+ if [ -n `echo $app_type | grep "sdl"` ] && [ -z "$thread_support" ] \
+    && [ "$ARG_THREAD_SUPPORT" != "0" ]; then
+   thread_support="HAVE_SDL_THREADS"
+   if [ "$ARG_THREAD_SUPPORT" = "1" ]; then
+     echo "Selected SDL threads"
+   else
+     echo "WARNING: Falling back to SDL threads"
+   fi
+ fi
 }
 
 #
@@ -994,6 +1057,11 @@ help() {
     --thumb           Build with -mthumb (for ARM builds)
     --no-thumb        The opposite of --thumb (don't use thumb even for targets
                       where this is the default
+    --sdl-threads     Force use of SDL threads. They have inferior performance,
+                      but are better debuggable with GDB
+    --no-sdl-threads  Disallow use of SDL threads. This prevents the default
+                      behavior of falling back to them if no native thread
+                      support was found.
     --prefix          Target installation directory
     --help            Shows this message (must not be used with other options)
 
@@ -1015,6 +1083,7 @@ ARG_VOICE=
 ARG_ARM_EABI=
 ARG_ARM_THUMB=
 ARG_PREFIX="$PREFIX"
+ARG_THREAD_SUPPORT=
 err=
 for arg in "$@"; do
 	case "$arg" in
@@ -1035,6 +1104,9 @@ for arg in "$@"; do
 		--no-eabi)    ARG_ARM_EABI=0;;
 		--thumb)      ARG_ARM_THUMB=1;;
 		--no-thumb)   ARG_ARM_THUMB=0;;
+        --sdl-threads)ARG_THREAD_SUPPORT=1;;
+        --no-sdl-threads)
+                      ARG_THREAD_SUPPORT=0;;
         --prefix=*)   ARG_PREFIX=`echo "$arg" | cut -d = -f 2`;;
 		--help)       help;;
 		*)            err=1; echo "[ERROR] Option '$arg' unsupported";;
@@ -3326,6 +3398,7 @@ sed > autoconf.h \
  -e "s<^#undef DO_BOOTCHART<$use_bootchart<g" \
  -e "s<@config_rtc@<$config_rtc<g" \
  -e "s<@have_rtc_alarm@<$have_rtc_alarm<g" \
+ -e "s<@thread_support@<$thread_support<g" \
  -e "s<@RBDIR@<${rbdir}<g" \
  -e "s<@sharepath@<${sharedir}<g" \
  -e "s<@binpath@<${bindir}<g" \
@@ -3362,6 +3435,9 @@ sed > autoconf.h \
 @config_rtc@
 @have_rtc_alarm@
 
+/* the threading backend we use */
+#define @thread_support@
+
 /* lcd dimensions for application builds from configure */
 @lcd_width@
 @lcd_height@
-- 
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