diff --git a/.gitignore b/.gitignore
index a1c45f1..ed501c9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,4 +46,9 @@ nasal.exe
 # misc
 .vscode
 dump
-a.ppm
\ No newline at end of file
+
+# macOS special cache directory
+.DS_Store
+
+# ppm picture generated by ppmgen.nas
+*.ppm
\ No newline at end of file
diff --git a/main.cpp b/main.cpp
index a7d9934..b5cef16 100644
--- a/main.cpp
+++ b/main.cpp
@@ -6,10 +6,9 @@ const u32 VM_CODEINFO =0x04;
 const u32 VM_EXECTIME =0x08;
 const u32 VM_OPCALLNUM=0x10;
 const u32 VM_EXEC     =0x20;
-const u32 VM_DBGINFO  =0x40;
+const u32 VM_DETAIL   =0x40;
 const u32 VM_DEBUG    =0x80;
 const u32 VM_OPTIMIZE =0x100;
-const u32 VM_SHOWPATH =0x200;
 
 void help()
 {
@@ -33,12 +32,12 @@ void help()
     <<"    -t,   --time    | get the running time.\n"
     <<"    -o,   --opcnt   | count used operands.\n"
     <<"                    | available in debug mode.\n"
-    <<"    -d,   --detail  | get detail crash info.\n"
+    <<"    -d,   --detail  | get detail runtime crash info.\n"
+    <<"                    | get detail linker path-not-found info.\n"
     <<"                    | get garbage collector info if didn't crash.\n"
     <<"    -op,  --optimize| use optimizer(beta).\n"
     <<"                    | if want to use -op and run, please use -op -e/-t/-d.\n"
     <<"    -dbg, --debug   | debug mode (this will ignore -t -d).\n"
-    <<"    -cp,  --chkpath | show path if linker cannot find files.\n"
     <<"file:\n"
     <<"    input file name to execute.\n"
     <<"argv:\n"
@@ -90,7 +89,7 @@ void execute(const string& file,const std::vector<string>& argv,const u32 cmd)
     // parser gets lexer's token list to compile
     parse.compile(lexer);
     // linker gets parser's ast and load import files to this ast
-    linker.link(parse,file,cmd&VM_SHOWPATH);
+    linker.link(parse,file,cmd&VM_DETAIL);
     // optimizer does simple optimization on ast
     if(cmd&VM_OPTIMIZE)
         optimize(parse.ast());
@@ -108,12 +107,12 @@ void execute(const string& file,const std::vector<string>& argv,const u32 cmd)
     else if(cmd&VM_EXECTIME)
     {
         auto start=std::chrono::high_resolution_clock::now();
-        vm.run(gen,linker,argv,cmd&VM_DBGINFO);
+        vm.run(gen,linker,argv,cmd&VM_DETAIL);
         auto end=std::chrono::high_resolution_clock::now();
         std::clog<<"process exited after "<<(end-start).count()*1.0/std::chrono::high_resolution_clock::duration::period::den<<"s.\n";
     }
     else if(cmd&VM_EXEC)
-        vm.run(gen,linker,argv,cmd&VM_DBGINFO);
+        vm.run(gen,linker,argv,cmd&VM_DETAIL);
 }
 
 i32 main(i32 argc,const char* argv[])
@@ -143,10 +142,9 @@ i32 main(i32 argc,const char* argv[])
         {"--exec",VM_EXEC},{"-e",VM_EXEC},
         {"--opcnt",VM_OPCALLNUM},{"-o",VM_OPCALLNUM},
         {"--time",VM_EXECTIME|VM_EXEC},{"-t",VM_EXECTIME|VM_EXEC},
-        {"--detail",VM_DBGINFO|VM_EXEC},{"-d",VM_DBGINFO|VM_EXEC},
+        {"--detail",VM_DETAIL|VM_EXEC},{"-d",VM_DETAIL|VM_EXEC},
         {"--optimize",VM_OPTIMIZE},{"-op",VM_OPTIMIZE},
-        {"--debug",VM_DEBUG},{"-dbg",VM_DEBUG},
-        {"--chkpath",VM_SHOWPATH},{"-cp",VM_SHOWPATH} // this could be merged to -d
+        {"--debug",VM_DEBUG},{"-dbg",VM_DEBUG}
     };
     u32 cmd=0;
     string filename;
diff --git a/nasal.h b/nasal.h
index 6406b44..8e05bf7 100644
--- a/nasal.h
+++ b/nasal.h
@@ -52,7 +52,7 @@ using std::string;
 
 const u32 STACK_DEPTH=1024;
 
-inline f64 hex_to_double(const char* str)
+inline f64 hex2f(const char* str)
 {
     f64 ret=0;
     for(;*str;++str)
@@ -69,7 +69,7 @@ inline f64 hex_to_double(const char* str)
     }
     return ret;
 }
-inline f64 oct_to_double(const char* str)
+inline f64 oct2f(const char* str)
 {
     f64 ret=0;
     for(;*str;++str)
@@ -82,7 +82,10 @@ inline f64 oct_to_double(const char* str)
     }
     return ret;
 }
-inline f64 dec_to_double(const char* str)
+// we have the same reason not using atof here just as andy's interpreter does.
+// it is not platform independent, and may have strange output.
+// so we write a new function here to convert str to number manually.
+inline f64 dec2f(const char* str)
 {
     f64 ret=0,negative=1,num_pow=0;
     while('0'<=*str && *str<='9')
@@ -124,11 +127,11 @@ f64 str2num(const char* str)
     if(!*str)
         return nan("");
     if(str[0]=='0' && str[1]=='x')
-        res=hex_to_double(str+2);
+        res=hex2f(str+2);
     else if(str[0]=='0' && str[1]=='o')
-        res=oct_to_double(str+2);
+        res=oct2f(str+2);
     else
-        res=dec_to_double(str);
+        res=dec2f(str);
     return negative?-res:res;
 }
 
diff --git a/test/ppmgen.nas b/test/ppmgen.nas
index f8e4106..fa80fd8 100644
--- a/test/ppmgen.nas
+++ b/test/ppmgen.nas
@@ -1,20 +1,24 @@
 var RD=func(i,j){
-    return chr(bits.u32_and(255,j*0.25+i*0.001));
+    return bits.u32_and(255,j/255*255.999);
 }
 var GR=func(i,j){
-    return chr(bits.u32_and(255,j*0.15));
+    return bits.u32_and(255,i/255*255.999);
 }
 var BL=func(i,j){
-    return chr(bits.u32_and(255,j*0.05));
+    return bits.u32_and(255,0.25*255.999);
 }
 var pixel_write=func(fd,i,j){
-    var color=RD(i,j)~GR(i,j)~BL(i,j);
+    var color=RD(i,j)~" "~GR(i,j)~" "~BL(i,j)~" ";
     io.write(fd,color);
 }
 
 var fd=io.open("a.ppm","wb");
-io.write(fd,"P6\n512 512\n255\n");
-for(var i=0;i<512;i+=1)
-    for(var j=0;j<512;j+=1)
+# P3 use ASCII number
+# P6 use binary character
+io.write(fd,"P3\n256 256\n255\n");
+for(var i=255;i>=0;i-=1){
+    for(var j=0;j<256;j+=1)
         pixel_write(fd,i,j);
+    io.write(fd,"\n");
+}
 io.close(fd);
\ No newline at end of file