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/*-------------------------------------------------------------------
-- TITLE: Plasma CPU in software.  Executes MIPS(tm) opcodes.
-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)
-- DATE CREATED: 1/31/01
-- FILENAME: mlite.c
-- PROJECT: Plasma CPU core
-- COPYRIGHT: Software placed into the public domain by the author.
--    Software 'as is' without warranty.  Author liable for nothing.
-- DESCRIPTION:
--   Plasma CPU simulator in C code.
--   This file served as the starting point for the VHDL code.
--   Assumes running on a little endian PC.
--------------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
 
//#define ENABLE_CACHE
 
#define MEM_SIZE (1024*1024*2)
#define ntohs(A) ( ((A)>>8) | (((A)&0xff)<<8) )
#define htons(A) ntohs(A)
#define ntohl(A) ( ((A)>>24) | (((A)&0xff0000)>>8) | (((A)&0xff00)<<8) | ((A)<<24) )
#define htonl(A) ntohl(A)
 
#ifndef WIN32
#define getch getchar
void Sleep(unsigned long value)
{
   volatile unsigned long count = value*1000000;
   while(--count > 0) ;
}
#else
#include <conio.h>
extern void __stdcall Sleep(unsigned long value);
#endif
 
#define UART_WRITE        0x20000000
#define UART_READ         0x20000000
#define IRQ_MASK          0x20000010
#define IRQ_STATUS        0x20000020
#define CONFIG_REG        0x20000070
#define MMU_PROCESS_ID    0x20000080
#define MMU_FAULT_ADDR    0x20000090
#define MMU_TLB           0x200000a0
 
#define IRQ_UART_READ_AVAILABLE  0x001
#define IRQ_UART_WRITE_AVAILABLE 0x002
#define IRQ_COUNTER18_NOT        0x004
#define IRQ_COUNTER18            0x008
#define IRQ_MMU                  0x200
 
#define MMU_ENTRIES 4
#define MMU_MASK (1024*4-1)
typedef struct
{
   unsigned long virtualAddress;
   unsigned long physicalAddress;
} MmuEntry;
 
typedef struct {
   long r[32];
   long pc, pc_next, epc;
   unsigned long hi;
   unsigned long lo;
   long status;
   long userMode;
   long processId;
   long exceptionId;
   long faultAddr;
   long irqStatus;
   long skip;
   unsigned char *mem;
   long wakeup;
   long big_endian;
   MmuEntry mmuEntry[MMU_ENTRIES];
} State;
 
static char *opcode_string[]={
   "SPECIAL","REGIMM","J","JAL","BEQ","BNE","BLEZ","BGTZ",
   "ADDI","ADDIU","SLTI","SLTIU","ANDI","ORI","XORI","LUI",
   "COP0","COP1","COP2","COP3","BEQL","BNEL","BLEZL","BGTZL",
   "?","?","?","?","?","?","?","?",
   "LB","LH","LWL","LW","LBU","LHU","LWR","?",
   "SB","SH","SWL","SW","?","?","SWR","CACHE",
   "LL","LWC1","LWC2","LWC3","?","LDC1","LDC2","LDC3"
   "SC","SWC1","SWC2","SWC3","?","SDC1","SDC2","SDC3"
};
 
static char *special_string[]={
   "SLL","?","SRL","SRA","SLLV","?","SRLV","SRAV",
   "JR","JALR","MOVZ","MOVN","SYSCALL","BREAK","?","SYNC",
   "MFHI","MTHI","MFLO","MTLO","?","?","?","?",
   "MULT","MULTU","DIV","DIVU","?","?","?","?",
   "ADD","ADDU","SUB","SUBU","AND","OR","XOR","NOR",
   "?","?","SLT","SLTU","?","DADDU","?","?",
   "TGE","TGEU","TLT","TLTU","TEQ","?","TNE","?",
   "?","?","?","?","?","?","?","?"
};
 
static char *regimm_string[]={
   "BLTZ","BGEZ","BLTZL","BGEZL","?","?","?","?",
   "TGEI","TGEIU","TLTI","TLTIU","TEQI","?","TNEI","?",
   "BLTZAL","BEQZAL","BLTZALL","BGEZALL","?","?","?","?",
   "?","?","?","?","?","?","?","?"
};
 
static unsigned long HWMemory[8];
 
 
static long mem_read(State *s, long size, unsigned long address)
{
   unsigned long value=0, ptr;
 
   s->irqStatus |= IRQ_UART_WRITE_AVAILABLE;
   switch(address)
   {
      case UART_READ:
         if(kbhit())
            HWMemory[0] = getch();
         s->irqStatus &= ~IRQ_UART_READ_AVAILABLE; //clear bit
         return HWMemory[0];
      case IRQ_MASK:
         return HWMemory[1];
      case IRQ_MASK + 4:
         Sleep(10);
         return 0;
      case IRQ_STATUS:
         if(kbhit())
            s->irqStatus |= IRQ_UART_READ_AVAILABLE;
         return s->irqStatus;
      case MMU_PROCESS_ID:
         return s->processId;
      case MMU_FAULT_ADDR:
         return s->faultAddr;
   }
 
   ptr = (unsigned long)s->mem + (address % MEM_SIZE);
 
   if(0x10000000 <= address && address < 0x10000000 + 1024*1024)
      ptr = (unsigned long)s->mem + address - 0x10000000;
   else if(address < 1024*8)
      ptr += 1024*1024;
 
   switch(size)
   {
      case 4:
         if(address & 3)
            printf("Unaligned access PC=0x%x address=0x%x\n", s->pc, address);
         assert((address & 3) == 0);
         value = *(long*)ptr;
         if(s->big_endian)
            value = ntohl(value);
         break;
      case 2:
         assert((address & 1) == 0);
         value = *(unsigned short*)ptr;
         if(s->big_endian)
            value = ntohs((unsigned short)value);
         break;
      case 1:
         value = *(unsigned char*)ptr;
         break;
      default:
         printf("ERROR");
   }
   return(value);
}
 
static void mem_write(State *s, long size, long unsigned address, unsigned long value)
{
   static char_count=0;
   unsigned long ptr;
 
   switch(address)
   {
      case UART_WRITE:
         putch(value);
         return;
      case IRQ_MASK:
         HWMemory[1] = value;
         return;
      case IRQ_STATUS:
         s->irqStatus = value;
         return;
      case CONFIG_REG:
         return;
      case MMU_PROCESS_ID:
         //printf("processId=%d\n", value);
         s->processId = value;
         return;
   }
   if(MMU_TLB <= address && address <= MMU_TLB+MMU_ENTRIES * 8)
   {
      //printf("TLB 0x%x 0x%x\n", address - MMU_TLB, value);
      ptr = (unsigned long)s->mmuEntry + address - MMU_TLB;
      *(int*)ptr = value;
      s->irqStatus &= ~IRQ_MMU;
      return;
   }
 
   ptr = (unsigned long)s->mem + (address % MEM_SIZE);
 
   if(0x10000000 <= address && address < 0x10000000 + 1024*1024)
      ptr = (unsigned long)s->mem + address - 0x10000000;
   else if(address < 1024*8)
      ptr += 1024*1024;
 
   switch(size)
   {
      case 4:
         assert((address & 3) == 0);
         if(s->big_endian)
            value = htonl(value);
         *(long*)ptr = value;
         break;
      case 2:
         assert((address & 1) == 0);
         if(s->big_endian)
            value = htons((unsigned short)value);
         *(short*)ptr = (unsigned short)value;
         break;
      case 1:
         *(char*)ptr = (unsigned char)value;
         break;
      default:
         printf("ERROR");
   }
}
 
#ifdef ENABLE_CACHE
/************* Optional MMU and cache implementation *************/
/* TAG = VirtualAddress | ProcessId | WriteableBit */
unsigned long mmu_lookup(State *s, unsigned long processId,
                         unsigned long address, int write)
{
   int i;
   unsigned long compare, tag;
 
   if(processId == 0 || s->userMode == 0)
      return address;
   //if(address < 0x30000000)
   //   return address;
   compare = (address & ~MMU_MASK) | (processId << 1);
   for(i = 0; i < MMU_ENTRIES; ++i)
   {
      tag = s->mmuEntry[i].virtualAddress;
      if((tag & ~1) == compare && (write == 0 || (tag & 1)))
         return s->mmuEntry[i].physicalAddress | (address & MMU_MASK);
   }
   //printf("\nMMUTlbMiss 0x%x PC=0x%x w=%d pid=%d user=%d\n", 
   //   address, s->pc, write, processId, s->userMode);
   //printf("m");
   s->exceptionId = 1;
   s->faultAddr = address & ~MMU_MASK;
   s->irqStatus |= IRQ_MMU;
   return address;
}
 
 
#define CACHE_SET_ASSOC_LN2   0
#define CACHE_SET_ASSOC       (1 << CACHE_SET_ASSOC_LN2)
#define CACHE_SIZE_LN2        (13 - CACHE_SET_ASSOC_LN2)  //8 KB
#define CACHE_SIZE            (1 << CACHE_SIZE_LN2)
#define CACHE_LINE_SIZE_LN2   5                           //32 bytes
#define CACHE_LINE_SIZE       (1 << CACHE_LINE_SIZE_LN2)
 
static long cacheData[CACHE_SET_ASSOC][CACHE_SIZE/sizeof(long)];
static long cacheAddr[CACHE_SET_ASSOC][CACHE_SIZE/CACHE_LINE_SIZE];
static long cacheSetNext;
static long cacheMiss, cacheWriteBack, cacheCount;
 
static void cache_init(void)
{
   int set, i;
   for(set = 0; set < CACHE_SET_ASSOC; ++set)
   {
      for(i = 0; i < CACHE_SIZE/CACHE_LINE_SIZE; ++i)
         cacheAddr[set][i] = 0xffff0000;
   }
}
 
/* Write-back cache memory tagged by virtual address and processId */
/* TAG = virtualAddress | processId | dirtyBit */
static int cache_load(State *s, unsigned long address, int write)
{
   int set, i, pid, miss, offsetAddr, offsetData, offsetMem;
   unsigned long addrTagMatch, addrPrevMatch=0;
   unsigned long addrPrev;
   unsigned long addressPhysical, tag;
 
   ++cacheCount;
   addrTagMatch = address & ~(CACHE_SIZE-1);
   offsetAddr = (address & (CACHE_SIZE-1)) >> CACHE_LINE_SIZE_LN2;
 
   /* Find match */
   miss = 1;
   for(set = 0; set < CACHE_SET_ASSOC; ++set)
   {
      addrPrevMatch = cacheAddr[set][offsetAddr] & ~(CACHE_SIZE-1);
      if(addrPrevMatch == addrTagMatch)
      {
         miss = 0;
         break;
      }
   }
 
   /* Cache miss? */
   if(miss)
   {
      ++cacheMiss;
      set = cacheSetNext;
      cacheSetNext = (cacheSetNext + 1) & (CACHE_SET_ASSOC-1);
   }
   else if(write || (address >> 28) != 0x1)
   {
      tag = cacheAddr[set][offsetAddr];
      pid = (tag & (CACHE_SIZE-1)) >> 1;
      if(pid != s->processId)
         miss = 1;
   }
 
   if(miss)
   {
      offsetData = address & (CACHE_SIZE-1) & ~(CACHE_LINE_SIZE-1);
 
      /* Cache line dirty? */
      if(cacheAddr[set][offsetAddr] & 1)
      {
         /* Write back cache line */
         tag = cacheAddr[set][offsetAddr];
         addrPrev = tag & ~(CACHE_SIZE-1);
         addrPrev |= address & (CACHE_SIZE-1);
         pid = (tag & (CACHE_SIZE-1)) >> 1;
         addressPhysical = mmu_lookup(s, pid, addrPrev, 1);   //virtual->physical
         if(s->exceptionId)
            return 0;
         offsetMem = addressPhysical & ~(CACHE_LINE_SIZE-1);
         for(i = 0; i < CACHE_LINE_SIZE; i += 4)
            mem_write(s, 4, offsetMem + i, cacheData[set][(offsetData + i) >> 2]);
         ++cacheWriteBack;
      }
 
      /* Read cache line */
      addressPhysical = mmu_lookup(s, s->processId, address, write); //virtual->physical
      if(s->exceptionId)
         return 0;
      offsetMem = addressPhysical & ~(CACHE_LINE_SIZE-1);
      cacheAddr[set][offsetAddr] = addrTagMatch;
      for(i = 0; i < CACHE_LINE_SIZE; i += 4)
         cacheData[set][(offsetData + i) >> 2] = mem_read(s, 4, offsetMem + i);
   }
   cacheAddr[set][offsetAddr] |= write;
   return set;
}
 
static long cache_read(State *s, long size, unsigned long address)
{
   int set, offset;
   long value;
 
   if((address >> 28) == 0x2) // && (s->processId == 0 || s->userMode == 0))
      return mem_read(s, size, address);
 
   set = cache_load(s, address, 0);
   if(s->exceptionId)
      return 0;
   offset = (address & (CACHE_SIZE-1)) >> 2;
   value = cacheData[set][offset];
   if(s->big_endian)
      address ^= 3;
   switch(size)
   {
      case 2:
         value = (value >> ((address & 2) << 3)) & 0xffff;
         break;
      case 1:
         value = (value >> ((address & 3) << 3)) & 0xff;
         break;
   }
   return value;
}
 
static void cache_write(State *s, long size, long unsigned address, unsigned long value)
{
   int set, offset;
   unsigned long mask;
 
   if((address >> 28) == 0x2) // && (s->processId == 0 || s->userMode == 0))
   {
      mem_write(s, size, address, value);
      return;
   }
 
   set = cache_load(s, address, 1);
   if(s->exceptionId)
      return;
   offset = (address & (CACHE_SIZE-1)) >> 2;
   if(s->big_endian)
      address ^= 3;
   switch(size)
   {
      case 2:
         value &= 0xffff;
         value |= value << 16;
         mask = 0xffff << ((address & 2) << 3);
         break;
      case 1:
         value &= 0xff;
         value |= (value << 8) | (value << 16) | (value << 24);
         mask = 0xff << ((address & 3) << 3);
         break;
      case 4:
      default:
         mask = 0xffffffff;
         break;
   }
   cacheData[set][offset] = (value & mask) | (cacheData[set][offset] & ~mask);
}
 
#define mem_read cache_read
#define mem_write cache_write
/************* End optional cache implementation *************/
#else
static void cache_init(void) {}
#endif
 
void mult_big(unsigned long a,
              unsigned long b,
              unsigned long *hi,
              unsigned long *lo)
{
   unsigned long ahi, alo, bhi, blo;
   unsigned long c0, c1, c2;
   unsigned long c1_a, c1_b;
 
   ahi = a >> 16;
   alo = a & 0xffff;
   bhi = b >> 16;
   blo = b & 0xffff;
 
   c0 = alo * blo;
   c1_a = ahi * blo;
   c1_b = alo * bhi;
   c2 = ahi * bhi;
 
   c2 += (c1_a >> 16) + (c1_b >> 16);
   c1 = (c1_a & 0xffff) + (c1_b & 0xffff) + (c0 >> 16);
   c2 += (c1 >> 16);
   c0 = (c1 << 16) + (c0 & 0xffff);
   *hi = c2;
   *lo = c0;
}
 
void mult_big_signed(long a,
                     long b,
                     unsigned long *hi,
                     unsigned long *lo)
{
   unsigned long ahi, alo, bhi, blo;
   unsigned long c0, c1, c2;
   unsigned long c1_a, c1_b;
 
   ahi = a >> 16;
   alo = a & 0xffff;
   bhi = b >> 16;
   blo = b & 0xffff;
 
   c0 = alo * blo;
   c1_a = ahi * blo;
   c1_b = alo * bhi;
   c2 = ahi * bhi;
 
   c2 += (c1_a >> 16) + (c1_b >> 16);
   c1 = (c1_a & 0xffff) + (c1_b & 0xffff) + (c0 >> 16);
   c2 += (c1 >> 16);
   c0 = (c1 << 16) + (c0 & 0xffff);
   *hi = c2;
   *lo = c0;
}
 
//execute one cycle of a Plasma CPU
void cycle(State *s, int show_mode)
{
   unsigned long opcode;
   unsigned long op, rs, rt, rd, re, func, imm, target;
   long imm_shift, branch=0, lbranch=2, skip2=0;
   long *r=s->r;
   unsigned long *u=(unsigned long*)s->r;
   unsigned long ptr, epc, rSave;
 
   opcode = mem_read(s, 4, s->pc);
   op = (opcode >> 26) & 0x3f;
   rs = (opcode >> 21) & 0x1f;
   rt = (opcode >> 16) & 0x1f;
   rd = (opcode >> 11) & 0x1f;
   re = (opcode >> 6) & 0x1f;
   func = opcode & 0x3f;
   imm = opcode & 0xffff;
   imm_shift = (((long)(short)imm) << 2) - 4;
   target = (opcode << 6) >> 4;
   ptr = (short)imm + r[rs];
   r[0] = 0;
   if(show_mode)
   {
      printf("%8.8lx %8.8lx ", s->pc, opcode);
      if(op == 0)
         printf("%8s ", special_string[func]);
      else if(op == 1)
         printf("%8s ", regimm_string[rt]);
      else
         printf("%8s ", opcode_string[op]);
      printf("$%2.2ld $%2.2ld $%2.2ld $%2.2ld ", rs, rt, rd, re);
      printf("%4.4lx", imm);
      if(show_mode == 1)
         printf(" r[%2.2d]=%8.8x r[%2.2d]=%8.8x", rs, r[rs], rt, r[rt]);
      printf("\n");
   }
   if(show_mode > 5)
      return;
   epc = s->pc + 4;
   if(s->pc_next != s->pc + 4)
      epc |= 2;  //branch delay slot
   s->pc = s->pc_next;
   s->pc_next = s->pc_next + 4;
   if(s->skip)
   {
      s->skip = 0;
      return;
   }
   rSave = r[rt];
   switch(op)
   {
      case 0x00:/*SPECIAL*/
         switch(func)
         {
            case 0x00:/*SLL*/  r[rd]=r[rt]<<re;          break;
            case 0x02:/*SRL*/  r[rd]=u[rt]>>re;          break;
            case 0x03:/*SRA*/  r[rd]=r[rt]>>re;          break;
            case 0x04:/*SLLV*/ r[rd]=r[rt]<<r[rs];       break;
            case 0x06:/*SRLV*/ r[rd]=u[rt]>>r[rs];       break;
            case 0x07:/*SRAV*/ r[rd]=r[rt]>>r[rs];       break;
            case 0x08:/*JR*/   s->pc_next=r[rs];         break;
            case 0x09:/*JALR*/ r[rd]=s->pc_next; s->pc_next=r[rs]; break;
            case 0x0a:/*MOVZ*/ if(!r[rt]) r[rd]=r[rs];   break;  /*IV*/
            case 0x0b:/*MOVN*/ if(r[rt]) r[rd]=r[rs];    break;  /*IV*/
            case 0x0c:/*SYSCALL*/ epc|=1; s->exceptionId=1; break;
            case 0x0d:/*BREAK*/   epc|=1; s->exceptionId=1; break;
            case 0x0f:/*SYNC*/ s->wakeup=1;              break;
            case 0x10:/*MFHI*/ r[rd]=s->hi;              break;
            case 0x11:/*FTHI*/ s->hi=r[rs];              break;
            case 0x12:/*MFLO*/ r[rd]=s->lo;              break;
            case 0x13:/*MTLO*/ s->lo=r[rs];              break;
            case 0x18:/*MULT*/ mult_big_signed(r[rs],r[rt],&s->hi,&s->lo); break;
            case 0x19:/*MULTU*/ mult_big(r[rs],r[rt],&s->hi,&s->lo); break;
            case 0x1a:/*DIV*/  s->lo=r[rs]/r[rt]; s->hi=r[rs]%r[rt]; break;
            case 0x1b:/*DIVU*/ s->lo=u[rs]/u[rt]; s->hi=u[rs]%u[rt]; break;
            case 0x20:/*ADD*/  r[rd]=r[rs]+r[rt];        break;
            case 0x21:/*ADDU*/ r[rd]=r[rs]+r[rt];        break;
            case 0x22:/*SUB*/  r[rd]=r[rs]-r[rt];        break;
            case 0x23:/*SUBU*/ r[rd]=r[rs]-r[rt];        break;
            case 0x24:/*AND*/  r[rd]=r[rs]&r[rt];        break;
            case 0x25:/*OR*/   r[rd]=r[rs]|r[rt];        break;
            case 0x26:/*XOR*/  r[rd]=r[rs]^r[rt];        break;
            case 0x27:/*NOR*/  r[rd]=~(r[rs]|r[rt]);     break;
            case 0x2a:/*SLT*/  r[rd]=r[rs]<r[rt];        break;
            case 0x2b:/*SLTU*/ r[rd]=u[rs]<u[rt];        break;
            case 0x2d:/*DADDU*/r[rd]=r[rs]+u[rt];        break;
            case 0x31:/*TGEU*/ break;
            case 0x32:/*TLT*/  break;
            case 0x33:/*TLTU*/ break;
            case 0x34:/*TEQ*/  break;
            case 0x36:/*TNE*/  break;
            default: printf("ERROR0(*0x%x~0x%x)\n", s->pc, opcode);
               s->wakeup=1;
         }
         break;
      case 0x01:/*REGIMM*/
         switch(rt) {
            case 0x10:/*BLTZAL*/ r[31]=s->pc_next;
            case 0x00:/*BLTZ*/   branch=r[rs]<0;    break;
            case 0x11:/*BGEZAL*/ r[31]=s->pc_next;
            case 0x01:/*BGEZ*/   branch=r[rs]>=0;   break;
            case 0x12:/*BLTZALL*/r[31]=s->pc_next;
            case 0x02:/*BLTZL*/  lbranch=r[rs]<0;   break;
            case 0x13:/*BGEZALL*/r[31]=s->pc_next;
            case 0x03:/*BGEZL*/  lbranch=r[rs]>=0;  break;
            default: printf("ERROR1\n"); s->wakeup=1;
          }
         break;
      case 0x03:/*JAL*/    r[31]=s->pc_next;
      case 0x02:/*J*/      s->pc_next=(s->pc&0xf0000000)|target; break;
      case 0x04:/*BEQ*/    branch=r[rs]==r[rt];     break;
      case 0x05:/*BNE*/    branch=r[rs]!=r[rt];     break;
      case 0x06:/*BLEZ*/   branch=r[rs]<=0;         break;
      case 0x07:/*BGTZ*/   branch=r[rs]>0;          break;
      case 0x08:/*ADDI*/   r[rt]=r[rs]+(short)imm;  break;
      case 0x09:/*ADDIU*/  u[rt]=u[rs]+(short)imm;  break;
      case 0x0a:/*SLTI*/   r[rt]=r[rs]<(short)imm;  break;
      case 0x0b:/*SLTIU*/  u[rt]=u[rs]<(unsigned long)(short)imm; break;
      case 0x0c:/*ANDI*/   r[rt]=r[rs]&imm;         break;
      case 0x0d:/*ORI*/    r[rt]=r[rs]|imm;         break;
      case 0x0e:/*XORI*/   r[rt]=r[rs]^imm;         break;
      case 0x0f:/*LUI*/    r[rt]=(imm<<16);         break;
      case 0x10:/*COP0*/
         if((opcode & (1<<23)) == 0)  //move from CP0
         {
            if(rd == 12)
               r[rt]=s->status;
            else
               r[rt]=s->epc;
         }
         else                         //move to CP0
         {
            s->status=r[rt]&1;
            if(s->processId && (r[rt]&2))
            {
               s->userMode|=r[rt]&2;
               //printf("CpuStatus=%d %d %d\n", r[rt], s->status, s->userMode);
               //s->wakeup = 1;
               //printf("pc=0x%x\n", epc);
            }
         }
         break;
//      case 0x11:/*COP1*/ break;
//      case 0x12:/*COP2*/ break;
//      case 0x13:/*COP3*/ break;
      case 0x14:/*BEQL*/   lbranch=r[rs]==r[rt];    break;
      case 0x15:/*BNEL*/   lbranch=r[rs]!=r[rt];    break;
      case 0x16:/*BLEZL*/  lbranch=r[rs]<=0;        break;
      case 0x17:/*BGTZL*/  lbranch=r[rs]>0;         break;
//      case 0x1c:/*MAD*/  break;   /*IV*/
      case 0x20:/*LB*/   r[rt]=(signed char)mem_read(s,1,ptr);  break;
      case 0x21:/*LH*/   r[rt]=(signed short)mem_read(s,2,ptr); break;
      case 0x22:/*LWL*/
                         //target=8*(ptr&3);
                         //r[rt]=(r[rt]&~(0xffffffff<<target))|
                         //      (mem_read(s,4,ptr&~3)<<target); break;
      case 0x23:/*LW*/   r[rt]=mem_read(s,4,ptr);   break;
      case 0x24:/*LBU*/  r[rt]=(unsigned char)mem_read(s,1,ptr); break;
      case 0x25:/*LHU*/  r[rt]=(unsigned short)mem_read(s,2,ptr); break;
      case 0x26:/*LWR*/
                         //target=32-8*(ptr&3);
                         //r[rt]=(r[rt]&~((unsigned long)0xffffffff>>target))|
                         //((unsigned long)mem_read(s,4,ptr&~3)>>target); 
                         break;
      case 0x28:/*SB*/   mem_write(s,1,ptr,r[rt]);  break;
      case 0x29:/*SH*/   mem_write(s,2,ptr,r[rt]);  break;
      case 0x2a:/*SWL*/
                         //mem_write(s,1,ptr,r[rt]>>24);  
                         //mem_write(s,1,ptr+1,r[rt]>>16);
                         //mem_write(s,1,ptr+2,r[rt]>>8);
                         //mem_write(s,1,ptr+3,r[rt]); break;
      case 0x2b:/*SW*/   mem_write(s,4,ptr,r[rt]);  break;
      case 0x2e:/*SWR*/  break; //fixme
      case 0x2f:/*CACHE*/break;
      case 0x30:/*LL*/   r[rt]=mem_read(s,4,ptr);   break;
//      case 0x31:/*LWC1*/ break;
//      case 0x32:/*LWC2*/ break;
//      case 0x33:/*LWC3*/ break;
//      case 0x35:/*LDC1*/ break;
//      case 0x36:/*LDC2*/ break;
//      case 0x37:/*LDC3*/ break;
//      case 0x38:/*SC*/     *(long*)ptr=r[rt]; r[rt]=1; break;
      case 0x38:/*SC*/     mem_write(s,4,ptr,r[rt]); r[rt]=1; break;
//      case 0x39:/*SWC1*/ break;
//      case 0x3a:/*SWC2*/ break;
//      case 0x3b:/*SWC3*/ break;
//      case 0x3d:/*SDC1*/ break;
//      case 0x3e:/*SDC2*/ break;
//      case 0x3f:/*SDC3*/ break;
      default: printf("ERROR2 address=0x%x opcode=0x%x\n", s->pc, opcode);
         s->wakeup=1;
   }
   s->pc_next += (branch || lbranch == 1) ? imm_shift : 0;
   s->pc_next &= ~3;
   s->skip = (lbranch == 0) | skip2;
 
   if(s->exceptionId)
   {
      r[rt] = rSave;
      s->epc = epc;
      s->pc_next = 0x3c;
      s->skip = 1;
      s->exceptionId = 0;
      s->userMode = 0;
      //s->wakeup = 1;
      return;
   }
}
 
void show_state(State *s)
{
   long i,j;
   printf("pid=%d userMode=%d, epc=0x%x\n", s->processId, s->userMode, s->epc);
   for(i = 0; i < 4; ++i)
   {
      printf("%2.2ld ", i * 8);
      for(j = 0; j < 8; ++j)
      {
         printf("%8.8lx ", s->r[i*8+j]);
      }
      printf("\n");
   }
   //printf("%8.8lx %8.8lx %8.8lx %8.8lx\n", s->pc, s->pc_next, s->hi, s->lo);
   j = s->pc;
   for(i = -4; i <= 8; ++i)
   {
      printf("%c", i==0 ? '*' : ' ');
      s->pc = j + i * 4;
      cycle(s, 10);
   }
   s->pc = j;
}
 
void do_debug(State *s)
{
   int ch;
   long i, j=0, watch=0, addr;
   s->pc_next = s->pc + 4;
   s->skip = 0;
   s->wakeup = 0;
   show_state(s);
   ch = ' ';
   for(;;)
   {
      if(ch != 'n')
      {
         if(watch)
            printf("0x%8.8lx=0x%8.8lx\n", watch, mem_read(s, 4, watch));
         printf("1=Debug 2=Trace 3=Step 4=BreakPt 5=Go 6=Memory ");
         printf("7=Watch 8=Jump 9=Quit> ");
      }
      ch = getch();
      if(ch != 'n')
         printf("\n");
      switch(ch)
      {
      case '1': case 'd': case ' ':
         cycle(s, 0); show_state(s); break;
      case 'n':
         cycle(s, 1); break;
      case '2': case 't':
         cycle(s, 0); printf("*"); cycle(s, 10); break;
      case '3': case 's':
         printf("Count> ");
         scanf("%ld", &j);
         for(i = 0; i < j; ++i)
            cycle(s, 1);
         show_state(s);
         break;
      case '4': case 'b':
         printf("Line> ");
         scanf("%lx", &j);
         printf("break point=0x%x\n", j);
         break;
      case '5': case 'g':
         s->wakeup = 0;
         cycle(s, 0);
         while(s->wakeup == 0)
         {
            if(s->pc == j)
               break;
            cycle(s, 0);
         }
         show_state(s);
         break;
      case 'G':
         s->wakeup = 0;
         cycle(s, 1);
         while(s->wakeup == 0)
         {
            if(s->pc == j)
               break;
            cycle(s, 1);
         }
         show_state(s);
         break;
      case '6': case 'm':
         printf("Memory> ");
         scanf("%lx", &j);
         for(i = 0; i < 8; ++i)
         {
            printf("%8.8lx ", mem_read(s, 4, j+i*4));
         }
         printf("\n");
         break;
      case '7': case 'w':
         printf("Watch> ");
         scanf("%lx", &watch);
         break;
      case '8': case 'j':
         printf("Jump> ");
         scanf("%lx", &addr);
         s->pc = addr;
         s->pc_next = addr + 4;
         show_state(s);
         break;
      case '9': case 'q':
         return;
      }
   }
}
/************************************************************/
 
int main(int argc,char *argv[])
{
   State state, *s=&state;
   FILE *in;
   long bytes, index;
   printf("Plasma emulator\n");
   memset(s, 0, sizeof(State));
   s->big_endian = 1;
   s->mem = (unsigned char*)malloc(MEM_SIZE);
   memset(s->mem, 0, MEM_SIZE);
   if(argc <= 1)
   {
      printf("   Usage:  mlite file.exe\n");
      printf("           mlite file.exe B   {for big_endian}\n");
      printf("           mlite file.exe L   {for little_endian}\n");
      printf("           mlite file.exe BD  {disassemble big_endian}\n");
      printf("           mlite file.exe LD  {disassemble little_endian}\n");
 
      return 0;
   }
   in = fopen(argv[1], "rb");
   if(in == NULL)
   {
      printf("Can't open file %s!\n",argv[1]);
      getch();
      return(0);
   }
   bytes = fread(s->mem, 1, MEM_SIZE, in);
   fclose(in);
   memcpy(s->mem + 1024*1024, s->mem, 1024*8);  //internal 8KB SRAM
   printf("Read %ld bytes.\n", bytes);
   cache_init();
   if(argc == 3 && argv[2][0] == 'B')
   {
      printf("Big Endian\n");
      s->big_endian = 1;
   }
   if(argc == 3 && argv[2][0] == 'L')
   {
      printf("Big Endian\n");
      s->big_endian = 0;
   }
   s->processId = 0;
   if(argc == 3 && argv[2][0] == 'S')
   {  /*make big endian*/
      printf("Big Endian\n");
      for(index = 0; index < bytes+3; index += 4)
      {
         *(unsigned long*)&s->mem[index] = htonl(*(unsigned long*)&s->mem[index]);
      }
      in = fopen("big.exe", "wb");
      fwrite(s->mem, bytes, 1, in);
      fclose(in);
      return(0);
   }
   if(argc == 3 && argv[2][1] == 'D')
   {  /*dump image*/
      for(index = 0; index < bytes; index += 4) {
         s->pc = index;
         cycle(s, 10);
      }
      free(s->mem);
      return(0);
   }
   s->pc = 0x0;
   index = mem_read(s, 4, 0);
   if(index == 0x3c1c1000)
      s->pc = 0x10000000;
   do_debug(s);
   free(s->mem);
   return(0);
}
 

Line No.	Rev	Author	Line
1	41	rhoads	`/*-------------------------------------------------------------------`
2	43	rhoads	`-- TITLE: Plasma CPU in software. Executes MIPS(tm) opcodes.`
3	41	rhoads	`-- AUTHOR: Steve Rhoads (rhoadss@yahoo.com)`
4			`-- DATE CREATED: 1/31/01`
5			`-- FILENAME: mlite.c`
6	43	rhoads	`-- PROJECT: Plasma CPU core`
7	41	rhoads	`-- COPYRIGHT: Software placed into the public domain by the author.`
8			`-- Software 'as is' without warranty. Author liable for nothing.`
9			`-- DESCRIPTION:`
10	43	rhoads	`-- Plasma CPU simulator in C code.`
11	41	rhoads	`-- This file served as the starting point for the VHDL code.`
12	194	rhoads	`-- Assumes running on a little endian PC.`
13	41	rhoads	`--------------------------------------------------------------------*/`
14			`#include <stdio.h>`
15			`#include <stdlib.h>`
16			`#include <string.h>`
17			`#include <ctype.h>`
18	137	rhoads	`#include <assert.h>`
19	41	rhoads
20	194	rhoads	`//#define ENABLE_CACHE`
21
22	41	rhoads	`#define MEM_SIZE (102410242)`
23			`#define ntohs(A) ( ((A)>>8) \| (((A)&0xff)<<8) )`
24			`#define htons(A) ntohs(A)`
25			`#define ntohl(A) ( ((A)>>24) \| (((A)&0xff0000)>>8) \| (((A)&0xff00)<<8) \| ((A)<<24) )`
26			`#define htonl(A) ntohl(A)`
27
28	137	rhoads	`#ifndef WIN32`
29	104	rhoads	`#define getch getchar`
30	137	rhoads	`void Sleep(unsigned long value)`
31			`{`
32			`volatile unsigned long count = value*1000000;`
33			`while(--count > 0) ;`
34			`}`
35			`#else`
36	194	rhoads	`#include <conio.h>`
37	137	rhoads	`extern void __stdcall Sleep(unsigned long value);`
38			`#endif`
39	41	rhoads
40	137	rhoads	`#define UART_WRITE 0x20000000`
41			`#define UART_READ 0x20000000`
42			`#define IRQ_MASK 0x20000010`
43			`#define IRQ_STATUS 0x20000020`
44	194	rhoads	`#define CONFIG_REG 0x20000070`
45			`#define MMU_PROCESS_ID 0x20000080`
46			`#define MMU_FAULT_ADDR 0x20000090`
47			`#define MMU_TLB 0x200000a0`
48	137	rhoads
49	194	rhoads	`#define IRQ_UART_READ_AVAILABLE 0x001`
50			`#define IRQ_UART_WRITE_AVAILABLE 0x002`
51			`#define IRQ_COUNTER18_NOT 0x004`
52			`#define IRQ_COUNTER18 0x008`
53			`#define IRQ_MMU 0x200`
54	137	rhoads
55	194	rhoads	`#define MMU_ENTRIES 4`
56			`#define MMU_MASK (1024*4-1)`
57			`typedef struct`
58			`{`
59			`unsigned long virtualAddress;`
60			`unsigned long physicalAddress;`
61			`} MmuEntry;`
62
63	41	rhoads	`typedef struct {`
64			`long r[32];`
65	194	rhoads	`long pc, pc_next, epc;`
66			`unsigned long hi;`
67			`unsigned long lo;`
68			`long status;`
69			`long userMode;`
70			`long processId;`
71			`long exceptionId;`
72			`long faultAddr;`
73			`long irqStatus;`
74	41	rhoads	`long skip;`
75	137	rhoads	`unsigned char *mem;`
76	41	rhoads	`long wakeup;`
77			`long big_endian;`
78	194	rhoads	`MmuEntry mmuEntry[MMU_ENTRIES];`
79	41	rhoads	`} State;`
80
81			`static char *opcode_string[]={`
82			`"SPECIAL","REGIMM","J","JAL","BEQ","BNE","BLEZ","BGTZ",`
83			`"ADDI","ADDIU","SLTI","SLTIU","ANDI","ORI","XORI","LUI",`
84			`"COP0","COP1","COP2","COP3","BEQL","BNEL","BLEZL","BGTZL",`
85			`"?","?","?","?","?","?","?","?",`
86			`"LB","LH","LWL","LW","LBU","LHU","LWR","?",`
87			`"SB","SH","SWL","SW","?","?","SWR","CACHE",`
88			`"LL","LWC1","LWC2","LWC3","?","LDC1","LDC2","LDC3"`
89			`"SC","SWC1","SWC2","SWC3","?","SDC1","SDC2","SDC3"`
90			`};`
91
92			`static char *special_string[]={`
93			`"SLL","?","SRL","SRA","SLLV","?","SRLV","SRAV",`
94			`"JR","JALR","MOVZ","MOVN","SYSCALL","BREAK","?","SYNC",`
95			`"MFHI","MTHI","MFLO","MTLO","?","?","?","?",`
96			`"MULT","MULTU","DIV","DIVU","?","?","?","?",`
97			`"ADD","ADDU","SUB","SUBU","AND","OR","XOR","NOR",`
98			`"?","?","SLT","SLTU","?","DADDU","?","?",`
99			`"TGE","TGEU","TLT","TLTU","TEQ","?","TNE","?",`
100			`"?","?","?","?","?","?","?","?"`
101			`};`
102
103			`static char *regimm_string[]={`
104			`"BLTZ","BGEZ","BLTZL","BGEZL","?","?","?","?",`
105			`"TGEI","TGEIU","TLTI","TLTIU","TEQI","?","TNEI","?",`
106			`"BLTZAL","BEQZAL","BLTZALL","BGEZALL","?","?","?","?",`
107			`"?","?","?","?","?","?","?","?"`
108			`};`
109
110	194	rhoads	`static unsigned long HWMemory[8];`
111	41	rhoads
112	137	rhoads
113			`static long mem_read(State *s, long size, unsigned long address)`
114	41	rhoads	`{`
115	137	rhoads	`unsigned long value=0, ptr;`
116
117	194	rhoads	`s->irqStatus \|= IRQ_UART_WRITE_AVAILABLE;`
118	137	rhoads	`switch(address)`
119			`{`
120			`case UART_READ:`
121			`if(kbhit())`
122			`HWMemory[0] = getch();`
123	194	rhoads	`s->irqStatus &= ~IRQ_UART_READ_AVAILABLE; //clear bit`
124	137	rhoads	`return HWMemory[0];`
125			`case IRQ_MASK:`
126			`return HWMemory[1];`
127			`case IRQ_MASK + 4:`
128			`Sleep(10);`
129			`return 0;`
130			`case IRQ_STATUS:`
131			`if(kbhit())`
132	194	rhoads	`s->irqStatus \|= IRQ_UART_READ_AVAILABLE;`
133			`return s->irqStatus;`
134			`case MMU_PROCESS_ID:`
135			`return s->processId;`
136			`case MMU_FAULT_ADDR:`
137			`return s->faultAddr;`
138	137	rhoads	`}`
139
140			`ptr = (unsigned long)s->mem + (address % MEM_SIZE);`
141
142			`if(0x10000000 <= address && address < 0x10000000 + 1024*1024)`
143	194	rhoads	`ptr = (unsigned long)s->mem + address - 0x10000000;`
144			`else if(address < 1024*8)`
145			`ptr += 1024*1024;`
146	137	rhoads
147			`switch(size)`
148			`{`
149			`case 4:`
150			`if(address & 3)`
151	194	rhoads	`printf("Unaligned access PC=0x%x address=0x%x\n", s->pc, address);`
152	137	rhoads	`assert((address & 3) == 0);`
153			`value = (long)ptr;`
154	194	rhoads	`if(s->big_endian)`
155	137	rhoads	`value = ntohl(value);`
156	41	rhoads	`break;`
157			`case 2:`
158	137	rhoads	`assert((address & 1) == 0);`
159			`value = (unsigned short)ptr;`
160	194	rhoads	`if(s->big_endian)`
161	137	rhoads	`value = ntohs((unsigned short)value);`
162	41	rhoads	`break;`
163			`case 1:`
164	137	rhoads	`value = (unsigned char)ptr;`
165	41	rhoads	`break;`
166	137	rhoads	`default:`
167			`printf("ERROR");`
168	41	rhoads	`}`
169			`return(value);`
170			`}`
171
172	137	rhoads	`static void mem_write(State *s, long size, long unsigned address, unsigned long value)`
173	41	rhoads	`{`
174			`static char_count=0;`
175			`unsigned long ptr;`
176	137	rhoads
177			`switch(address)`
178			`{`
179			`case UART_WRITE:`
180			`putch(value);`
181			`return;`
182			`case IRQ_MASK:`
183			`HWMemory[1] = value;`
184			`return;`
185			`case IRQ_STATUS:`
186	194	rhoads	`s->irqStatus = value;`
187	137	rhoads	`return;`
188	194	rhoads	`case CONFIG_REG:`
189			`return;`
190			`case MMU_PROCESS_ID:`
191			`//printf("processId=%d\n", value);`
192			`s->processId = value;`
193			`return;`
194	41	rhoads	`}`
195	194	rhoads	`if(MMU_TLB <= address && address <= MMU_TLB+MMU_ENTRIES * 8)`
196			`{`
197			`//printf("TLB 0x%x 0x%x\n", address - MMU_TLB, value);`
198			`ptr = (unsigned long)s->mmuEntry + address - MMU_TLB;`
199			`(int)ptr = value;`
200			`s->irqStatus &= ~IRQ_MMU;`
201			`return;`
202			`}`
203	137	rhoads
204			`ptr = (unsigned long)s->mem + (address % MEM_SIZE);`
205
206			`if(0x10000000 <= address && address < 0x10000000 + 1024*1024)`
207	194	rhoads	`ptr = (unsigned long)s->mem + address - 0x10000000;`
208			`else if(address < 1024*8)`
209			`ptr += 1024*1024;`
210	137	rhoads
211			`switch(size)`
212			`{`
213			`case 4:`
214			`assert((address & 3) == 0);`
215	194	rhoads	`if(s->big_endian)`
216	137	rhoads	`value = htonl(value);`
217			`(long)ptr = value;`
218	41	rhoads	`break;`
219			`case 2:`
220	137	rhoads	`assert((address & 1) == 0);`
221	194	rhoads	`if(s->big_endian)`
222	137	rhoads	`value = htons((unsigned short)value);`
223			`(short)ptr = (unsigned short)value;`
224	41	rhoads	`break;`
225			`case 1:`
226	137	rhoads	`(char)ptr = (unsigned char)value;`
227	41	rhoads	`break;`
228	137	rhoads	`default:`
229			`printf("ERROR");`
230	41	rhoads	`}`
231			`}`
232
233	194	rhoads	`#ifdef ENABLE_CACHE`
234			`/*********** Optional MMU and cache implementation ***********/`
235			`/* TAG = VirtualAddress \| ProcessId \| WriteableBit */`
236			`unsigned long mmu_lookup(State *s, unsigned long processId,`
237			`unsigned long address, int write)`
238			`{`
239			`int i;`
240			`unsigned long compare, tag;`
241
242			`if(processId == 0 \|\| s->userMode == 0)`
243			`return address;`
244			`//if(address < 0x30000000)`
245			`// return address;`
246			`compare = (address & ~MMU_MASK) \| (processId << 1);`
247			`for(i = 0; i < MMU_ENTRIES; ++i)`
248			`{`
249			`tag = s->mmuEntry[i].virtualAddress;`
250			`if((tag & ~1) == compare && (write == 0 \|\| (tag & 1)))`
251			`return s->mmuEntry[i].physicalAddress \| (address & MMU_MASK);`
252			`}`
253			`//printf("\nMMUTlbMiss 0x%x PC=0x%x w=%d pid=%d user=%d\n",`
254			`// address, s->pc, write, processId, s->userMode);`
255			`//printf("m");`
256			`s->exceptionId = 1;`
257			`s->faultAddr = address & ~MMU_MASK;`
258			`s->irqStatus \|= IRQ_MMU;`
259			`return address;`
260			`}`
261
262
263			`#define CACHE_SET_ASSOC_LN2 0`
264			`#define CACHE_SET_ASSOC (1 << CACHE_SET_ASSOC_LN2)`
265			`#define CACHE_SIZE_LN2 (13 - CACHE_SET_ASSOC_LN2) //8 KB`
266			`#define CACHE_SIZE (1 << CACHE_SIZE_LN2)`
267			`#define CACHE_LINE_SIZE_LN2 5 //32 bytes`
268			`#define CACHE_LINE_SIZE (1 << CACHE_LINE_SIZE_LN2)`
269
270			`static long cacheData[CACHE_SET_ASSOC][CACHE_SIZE/sizeof(long)];`
271			`static long cacheAddr[CACHE_SET_ASSOC][CACHE_SIZE/CACHE_LINE_SIZE];`
272			`static long cacheSetNext;`
273			`static long cacheMiss, cacheWriteBack, cacheCount;`
274
275			`static void cache_init(void)`
276			`{`
277			`int set, i;`
278			`for(set = 0; set < CACHE_SET_ASSOC; ++set)`
279			`{`
280			`for(i = 0; i < CACHE_SIZE/CACHE_LINE_SIZE; ++i)`
281			`cacheAddr[set][i] = 0xffff0000;`
282			`}`
283			`}`
284
285			`/* Write-back cache memory tagged by virtual address and processId */`
286			`/* TAG = virtualAddress \| processId \| dirtyBit */`
287			`static int cache_load(State *s, unsigned long address, int write)`
288			`{`
289			`int set, i, pid, miss, offsetAddr, offsetData, offsetMem;`
290			`unsigned long addrTagMatch, addrPrevMatch=0;`
291			`unsigned long addrPrev;`
292			`unsigned long addressPhysical, tag;`
293
294			`++cacheCount;`
295			`addrTagMatch = address & ~(CACHE_SIZE-1);`
296			`offsetAddr = (address & (CACHE_SIZE-1)) >> CACHE_LINE_SIZE_LN2;`
297
298			`/* Find match */`
299			`miss = 1;`
300			`for(set = 0; set < CACHE_SET_ASSOC; ++set)`
301			`{`
302			`addrPrevMatch = cacheAddr[set][offsetAddr] & ~(CACHE_SIZE-1);`
303			`if(addrPrevMatch == addrTagMatch)`
304			`{`
305			`miss = 0;`
306			`break;`
307			`}`
308			`}`
309
310			`/* Cache miss? */`
311			`if(miss)`
312			`{`
313			`++cacheMiss;`
314			`set = cacheSetNext;`
315			`cacheSetNext = (cacheSetNext + 1) & (CACHE_SET_ASSOC-1);`
316			`}`
317			`else if(write \|\| (address >> 28) != 0x1)`
318			`{`
319			`tag = cacheAddr[set][offsetAddr];`
320			`pid = (tag & (CACHE_SIZE-1)) >> 1;`
321			`if(pid != s->processId)`
322			`miss = 1;`
323			`}`
324
325			`if(miss)`
326			`{`
327			`offsetData = address & (CACHE_SIZE-1) & ~(CACHE_LINE_SIZE-1);`
328
329			`/* Cache line dirty? */`
330			`if(cacheAddr[set][offsetAddr] & 1)`
331			`{`
332			`/* Write back cache line */`
333			`tag = cacheAddr[set][offsetAddr];`
334			`addrPrev = tag & ~(CACHE_SIZE-1);`
335			`addrPrev \|= address & (CACHE_SIZE-1);`
336			`pid = (tag & (CACHE_SIZE-1)) >> 1;`
337			`addressPhysical = mmu_lookup(s, pid, addrPrev, 1); //virtual->physical`
338			`if(s->exceptionId)`
339			`return 0;`
340			`offsetMem = addressPhysical & ~(CACHE_LINE_SIZE-1);`
341			`for(i = 0; i < CACHE_LINE_SIZE; i += 4)`
342			`mem_write(s, 4, offsetMem + i, cacheData[set][(offsetData + i) >> 2]);`
343			`++cacheWriteBack;`
344			`}`
345
346			`/* Read cache line */`
347			`addressPhysical = mmu_lookup(s, s->processId, address, write); //virtual->physical`
348			`if(s->exceptionId)`
349			`return 0;`
350			`offsetMem = addressPhysical & ~(CACHE_LINE_SIZE-1);`
351			`cacheAddr[set][offsetAddr] = addrTagMatch;`
352			`for(i = 0; i < CACHE_LINE_SIZE; i += 4)`
353			`cacheData[set][(offsetData + i) >> 2] = mem_read(s, 4, offsetMem + i);`
354			`}`
355			`cacheAddr[set][offsetAddr] \|= write;`
356			`return set;`
357			`}`
358
359			`static long cache_read(State *s, long size, unsigned long address)`
360			`{`
361			`int set, offset;`
362			`long value;`
363
364			`if((address >> 28) == 0x2) // && (s->processId == 0 \|\| s->userMode == 0))`
365			`return mem_read(s, size, address);`
366
367			`set = cache_load(s, address, 0);`
368			`if(s->exceptionId)`
369			`return 0;`
370			`offset = (address & (CACHE_SIZE-1)) >> 2;`
371			`value = cacheData[set][offset];`
372			`if(s->big_endian)`
373			`address ^= 3;`
374			`switch(size)`
375			`{`
376			`case 2:`
377			`value = (value >> ((address & 2) << 3)) & 0xffff;`
378			`break;`
379			`case 1:`
380			`value = (value >> ((address & 3) << 3)) & 0xff;`
381			`break;`
382			`}`
383			`return value;`
384			`}`
385
386			`static void cache_write(State *s, long size, long unsigned address, unsigned long value)`
387			`{`
388			`int set, offset;`
389			`unsigned long mask;`
390
391			`if((address >> 28) == 0x2) // && (s->processId == 0 \|\| s->userMode == 0))`
392			`{`
393			`mem_write(s, size, address, value);`
394			`return;`
395			`}`
396
397			`set = cache_load(s, address, 1);`
398			`if(s->exceptionId)`
399			`return;`
400			`offset = (address & (CACHE_SIZE-1)) >> 2;`
401			`if(s->big_endian)`
402			`address ^= 3;`
403			`switch(size)`
404			`{`
405			`case 2:`
406			`value &= 0xffff;`
407			`value \|= value << 16;`
408			`mask = 0xffff << ((address & 2) << 3);`
409			`break;`
410			`case 1:`
411			`value &= 0xff;`
412			`value \|= (value << 8) \| (value << 16) \| (value << 24);`
413			`mask = 0xff << ((address & 3) << 3);`
414			`break;`
415			`case 4:`
416			`default:`
417			`mask = 0xffffffff;`
418			`break;`
419			`}`
420			`cacheData[set][offset] = (value & mask) \| (cacheData[set][offset] & ~mask);`
421			`}`
422
423			`#define mem_read cache_read`
424			`#define mem_write cache_write`
425			`/*********** End optional cache implementation ***********/`
426			`#else`
427			`static void cache_init(void) {}`
428			`#endif`
429
430	137	rhoads	`void mult_big(unsigned long a,`
431			`unsigned long b,`
432			`unsigned long *hi,`
433			`unsigned long *lo)`
434	41	rhoads	`{`
435	137	rhoads	`unsigned long ahi, alo, bhi, blo;`
436			`unsigned long c0, c1, c2;`
437			`unsigned long c1_a, c1_b;`
438	52	rhoads
439	137	rhoads	`ahi = a >> 16;`
440			`alo = a & 0xffff;`
441			`bhi = b >> 16;`
442			`blo = b & 0xffff;`
443	52	rhoads
444	137	rhoads	`c0 = alo * blo;`
445			`c1_a = ahi * blo;`
446			`c1_b = alo * bhi;`
447			`c2 = ahi * bhi;`
448	52	rhoads
449	137	rhoads	`c2 += (c1_a >> 16) + (c1_b >> 16);`
450			`c1 = (c1_a & 0xffff) + (c1_b & 0xffff) + (c0 >> 16);`
451			`c2 += (c1 >> 16);`
452			`c0 = (c1 << 16) + (c0 & 0xffff);`
453			`*hi = c2;`
454			`*lo = c0;`
455	41	rhoads	`}`
456
457	137	rhoads	`void mult_big_signed(long a,`
458			`long b,`
459			`unsigned long *hi,`
460			`unsigned long *lo)`
461			`{`
462			`unsigned long ahi, alo, bhi, blo;`
463			`unsigned long c0, c1, c2;`
464			`unsigned long c1_a, c1_b;`
465
466			`ahi = a >> 16;`
467			`alo = a & 0xffff;`
468			`bhi = b >> 16;`
469			`blo = b & 0xffff;`
470
471			`c0 = alo * blo;`
472			`c1_a = ahi * blo;`
473			`c1_b = alo * bhi;`
474			`c2 = ahi * bhi;`
475
476			`c2 += (c1_a >> 16) + (c1_b >> 16);`
477			`c1 = (c1_a & 0xffff) + (c1_b & 0xffff) + (c0 >> 16);`
478			`c2 += (c1 >> 16);`
479			`c0 = (c1 << 16) + (c0 & 0xffff);`
480			`*hi = c2;`
481			`*lo = c0;`
482			`}`
483
484	43	rhoads	`//execute one cycle of a Plasma CPU`
485	137	rhoads	`void cycle(State *s, int show_mode)`
486	41	rhoads	`{`
487			`unsigned long opcode;`
488	137	rhoads	`unsigned long op, rs, rt, rd, re, func, imm, target;`
489	194	rhoads	`long imm_shift, branch=0, lbranch=2, skip2=0;`
490	41	rhoads	`long *r=s->r;`
491			`unsigned long u=(unsigned long)s->r;`
492	194	rhoads	`unsigned long ptr, epc, rSave;`
493
494	137	rhoads	`opcode = mem_read(s, 4, s->pc);`
495			`op = (opcode >> 26) & 0x3f;`
496			`rs = (opcode >> 21) & 0x1f;`
497			`rt = (opcode >> 16) & 0x1f;`
498			`rd = (opcode >> 11) & 0x1f;`
499			`re = (opcode >> 6) & 0x1f;`
500			`func = opcode & 0x3f;`

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