From 75108e2e000f4382129d453c0fa9073b14d32f97 Mon Sep 17 00:00:00 2001
From: Determinant <ted.sybil@gmail.com>
Date: Wed, 2 Mar 2016 14:59:59 +0800
Subject: add options to main entry `nerv`; fix a bug in handling
 `cudaSetDevice` error

---
 nerv/lib/matrix/cumatrix.c |  2 +-
 nerv/matrix/cumatrix.c     |  2 +-
 nerv/nerv                  | 44 ++++++++++++++++++++++++++++++--------------
 3 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/nerv/lib/matrix/cumatrix.c b/nerv/lib/matrix/cumatrix.c
index ff2ea22..537fabb 100644
--- a/nerv/lib/matrix/cumatrix.c
+++ b/nerv/lib/matrix/cumatrix.c
@@ -78,10 +78,10 @@ void nerv_cuda_context_destroy(CuContext *context, Status *status) {
 
 void nerv_cuda_context_select_gpu(CuContext *context,
                                     int dev, Status *status) {
+    CUDA_SAFE_SYNC_CALL(cudaSetDevice(dev), status);
     free_cuda_handles(context, status);
     if (status->err_code != NERV_NORMAL)
         return;
-    CUDA_SAFE_SYNC_CALL(cudaSetDevice(dev), status);
     new_cuda_handles(context, status);
     if (status->err_code != NERV_NORMAL)
         return;
diff --git a/nerv/matrix/cumatrix.c b/nerv/matrix/cumatrix.c
index f6a4ed5..7d10895 100644
--- a/nerv/matrix/cumatrix.c
+++ b/nerv/matrix/cumatrix.c
@@ -9,7 +9,7 @@ const char *nerv_cuda_context_tname = "nerv.CuContext";
 int nerv_cuda_context_lua_select_gpu(lua_State *L) {
     Status status;
     nerv_cuda_context_select_gpu(luaT_checkudata(L, 1, nerv_cuda_context_tname),
-                            luaL_checkinteger(L, 1), &status);
+                            luaL_checkinteger(L, 2), &status);
     NERV_LUA_CHECK_STATUS(L, status);
     return 0;
 }
diff --git a/nerv/nerv b/nerv/nerv
index 4dd448c..9295290 100644
--- a/nerv/nerv
+++ b/nerv/nerv
@@ -1,13 +1,20 @@
 #! /usr/bin/env luajit
 require 'nerv'
-nerv.printf("*** NERV: A Lua-based toolkit for high-performance deep learning (alpha) ***\n")
-nerv.info("automatically initialize a default CuContext...")
-nerv.CuMatrix._default_context = nerv.CuContext()
-nerv.info("the default CuContext is ok")
+local options = {{"help", "h", "bool", default = false, desc = "print this help message"},
+                 {"use-cpu", "c", "bool", default = false, desc = "use CPU by default (instead of gpu by default)"},
+                 {"select-gpu", nil, "int", default = nil, desc = "select the GPU for computation, fallback to auto mode if not specified"}}
 
-nerv.info("automatically initialize a default MContext...")
-nerv.MMatrix._default_context = nerv.MContext()
-nerv.info("the default MContext is ok")
+local function print_help()
+    nerv.printf("Usage: <nerv_prog> [options] script.lua\n")
+    nerv.print_usage(options)
+end
+
+nerv.printf("*** NERV: A Lua-based toolkit for high-performance deep learning (alpha) ***\n")
+arg, opts = nerv.parse_args(arg, options)
+if #arg < 1 or opts["help"].val then
+    print_help()
+    return
+end
 
 -- only for backward compatibilty, will be removed in the future
 local function _add_profile_method(cls)
@@ -15,13 +22,24 @@ local function _add_profile_method(cls)
     cls.print_profile = function () c:print_profile() end
     cls.clear_profile = function () c:clear_profile() end
 end
-_add_profile_method(nerv.CuMatrix)
-_add_profile_method(nerv.MMatrix)
-
 
-if #arg < 1 then
-    return
+if not opts["use-cpu"].val then
+    nerv.info("automatically initialize a default CuContext...")
+    nerv.CuMatrix._default_context = nerv.CuContext()
+    nerv.info("the default CuContext is ok")
+    _add_profile_method(nerv.CuMatrix)
+    nerv.CuMatrix.select_gpu =
+            function (dev) nerv.CuMatrix._default_context:select_gpu(dev) end
+    if opts["select-gpu"].val then
+        nerv.CuMatrix.select_gpu(opts["select-gpu"].val)
+    end
 end
+
+nerv.info("automatically initialize a default MContext...")
+nerv.MMatrix._default_context = nerv.MContext()
+nerv.info("the default MContext is ok")
+_add_profile_method(nerv.MMatrix)
+
 local script = arg[1]
 local script_arg = {}
 for i = 2, #arg do
@@ -29,5 +47,3 @@ for i = 2, #arg do
 end
 arg = script_arg
 dofile(script)
-nerv.CuMatrix.print_profile()
-nerv.MMatrix.print_profile()
-- 
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