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/*-------------------------------------------------------------------

-- TITLE: MIPS CPU test code

-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)

-- DATE CREATED: 4/21/01

-- FILENAME: test.c

-- PROJECT: MIPS CPU core

-- COPYRIGHT: Software placed into the public domain by the author.

--    Software 'as is' without warranty.  Author liable for nothing.

-- DESCRIPTION:

--   The executable image of this file is used as input to the VHDL.

--

--   This file must not contain any global or static data since

--   there isn't a loader to relocate the .data segment and since

--   having static data causes the opcodes to begin at a different

--   location in the resulting executable file.

--

--   After being compiled with the Microsoft MIPS compiler, the program

--   convert will pull out the MIPS opcodes, and switch the executable

--   to Big Endian, and convert absolute jumps into relative jumps,

--   and save the opcodes in "code.txt".

--

--   The interrupt vector is set to address 0x30.

--------------------------------------------------------------------*/

#ifdef SIMULATE

#undef putchar

// The MIPS CPU VHDL supports a virtual UART.  All character writes

// to address 0xffff will be stored in the file "output.txt".

#define putchar(C) *(volatile unsigned char*)0xffff=(unsigned char)(C)

#endif

//The main entry point must be the first function

//The program convert will change the first opcode to setting 

//the stack pointer.

int main()

{

   int main2();

#ifdef MIPS

   __asm(".set noreorder");

   //The convertion tool will add two opcodes here

   __asm("ori $4,$0,0x1");

   __asm("mtc0 $4,$12");  //STATUS=1; enable interrupts

   __asm(".set reorder");

#endif

   main2();

#ifdef MIPS

   __asm(".set noreorder");

   __asm("nop");

   /*address 0x20 used for storing ISR register values*/

   __asm("nop");

   __asm("nop");

   __asm("nop");

   __asm("nop");

   __asm("nop");

   /*address 0x30 interrupt service routine*/

   __asm("sw $4,0x20($0)");

   __asm("sw $5,0x24($0)");

   __asm("ori $5,$0,0xffff");

   __asm("ori $4,$0,46");

//   __asm("sb $4,0($5)");   /*echo out '.'*/

   __asm("nop");

   /*normally clear the interrupt source here*/

   /*re-enable interrupts*/

   __asm("ori $4,$0,0x1");

   __asm("mtc0 $4,$12");   //STATUS=1; enable interrupts

   __asm("mfc0 $4, $14");  //C0_EPC=14

   __asm("nop");

   __asm("lw $5,0x24($0)");

   __asm("j $4");

   __asm("lw $4,0x20($0)");

   __asm(".set reorder");

#endif

}

char *strcpy2(char *s, const char *t)

{

   char *tmp=s;

   while((int)(*s++=*t++));

   return(tmp);

}

static void itoa2(long n, char *s, int base, long *digits)

{

   long i,j,sign;

   unsigned long n2;

   char number[20];

   for(i=0;i<15;++i) number[i]=' ';

   number[15]=0;

   if(n>=0||base!=10) sign=1;

   else sign=-1;

   n2=n*sign;

   for(j=14;j>=0;--j) {

      i=n2%base;

      n2/=base;

      number[j]=i<10?'0'+i:'a'+i-10;

      if(n2==0&&15-j>=*digits) break;

   }

   if(sign==-1) {

      number[--j]='-';

   }

   if(*digits==0||*digits<15-j) {

      strcpy2(s,&number[j]);

      *digits=15-j;

   } else {

      strcpy2(s,&number[15-*digits]);

   }

}

void print(long num,long base,long digits)

{

   volatile unsigned char *uart_base = (unsigned char *)0xffff;

   char *ptr,buffer[128];

   itoa2(num,buffer,base,&digits);

   ptr=buffer;

   while(*ptr) {

      putchar(*ptr++);          /* Put the character out */

      if(ptr[-1]=='\n') *--ptr='\r';

   }

}

void print_hex(unsigned long num)

{

   long i;

   unsigned long j;

   for(i=28;i>=0;i-=4) {

      j=((num>>i)&0xf);

      if(j<10) putchar('0'+j);

      else putchar('a'-10+j);

   }

}

int prime()

{

   int i,j,k;

   //show all prime numbers less than 1000

   for(i=3;i<1000;i+=2) {

      for(j=3;j<i;j+=2) {

         if(i%j==0) {

            j=0;

            break;

         }

      }

      if(j) {

         print(i,10,0);

         putchar(' ');

      }

   }

   putchar('\n');

   return 0;

}

int main2()

{

   long i,j,k;

   unsigned long m;

   char char_buf[16];

   short short_buf[16];

   long long_buf[16];

#if 1 

   //test shift

   j=0x12345678;

   for(i=0;i<32;++i) {

      print_hex(j>>i);

      putchar(' ');

   }

   putchar('\n');

   j=0x92345678;

   for(i=0;i<32;++i) {

      print_hex(j>>i);

      putchar(' ');

   }

   putchar('\n');

   j=0x12345678;

   for(i=0;i<32;++i) {

      print_hex(j<<i);

      putchar(' ');

   }

   putchar('\n');

   putchar('\n');

#endif

#if 1 

   //test multiply and divide

   j=7;

   for(i=0;i<=10;++i) {

      print(j*i,10,0);

      putchar(' ');

   }

   putchar('\n');

   j=0x321;

   for(i=0;i<=5;++i) {

      print_hex(j*(i+0x12345));

      putchar(' ');

   }

   putchar('\n');

   j=0x54321;

   for(i=0;i<=5;++i) {

      print_hex(j*(i+0x123));

      putchar(' ');

   }

   putchar('\n');

   j=0x12345;

   for(i=1;i<10;++i) {

      print_hex(j/i);

      putchar(' ');

   }

   putchar('\n');

   for(i=1;i<10;++i) {

      print_hex(j%i);

      putchar(' ');

   }

   putchar('\n');

   putchar('\n');

#endif

#if 1

   //test addition and subtraction

   j=0x1234;

   for(i=0;i<10;++i) {

      print_hex(j+i);

      putchar(' ');

   }

   putchar('\n');

   for(i=0;i<10;++i) {

      print_hex(j-i);

      putchar(' ');

   }

   putchar('\n');

   putchar('\n');

#endif

#if 1 

   //test bit operations

   i=0x1234;

   j=0x4321;

   print_hex(i&j);

   putchar(' ');

   print_hex(i|j);

   putchar(' ');

   print_hex(i^j);

   putchar(' ');

   print_hex(~i);

   putchar(' ');

   print_hex(i+0x12);

   putchar(' ');

   print_hex(i-0x12);

   putchar('\n');

   putchar('\n');

#endif

#if 1 

   //test memory access

   for(i=0;i<10;++i) {

      char_buf[i]=i;

      short_buf[i]=i;

      long_buf[i]=i;

   }

   for(i=0;i<10;++i) {

      j=char_buf[i];

      print(j,10,0);

      putchar(' ');

      j=short_buf[i];

      print(j,10,0);

      putchar(' ');

      j=long_buf[i];

      print(j,10,0);

      putchar('\n');

   }

   putchar('\n');

#endif

   prime();

   putchar('d'); putchar('o'); putchar('n'); putchar('e'); putchar('\n');

   for(;;) ;

}