what's wrong with my code?compile error

below is my code ,very simple,I compile it in nios IDE,not SDK,but I have created SDK with sopc builder.which header I need ?where can I find it ? In some sample ,I see "include "excalibur.h"",but some tell me this header was used in SDK ,not IDE? DO I need this file?when I put this file ,compile cann't find it too!thank very much! help me !

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# include <stdio.h># include "system.h"

int main()

{

na_timer1->np_timerperiodl = (short)(nasys_clock_freq & 0x0000ffff);

na_timer1->np_timerperiodh = (short)((nasys_clock_freq >> 16) & 0x0000ffff); // Set timer running, looping, no interrupts

na_timer1->np_timercontrol = np_timercontrol_start_mask+ np_timercontrol_cont_mask;

return 0;

}

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make -s all

Compiling hello_world.c...

../hello_world.c: In function `main&#39;:

../hello_world.c:22: error: `na_timer1&#39; undeclared (first use in this function)

../hello_world.c:22: error: (Each undeclared identifier is reported only once

../hello_world.c:22: error: for each function it appears in.)

../hello_world.c:22: error: `nasys_clock_freq&#39; undeclared (first use in this function)

../hello_world.c:24: error: `np_timercontrol_start_mask&#39; undeclared (first use in this function)

../hello_world.c:24: error: `np_timercontrol_cont_mask&#39; undeclared (first use in this function)

make: *** [obj/hello_world.o] Error 1

Build completed

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