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

* slite.c -- MIPS-I simulator based on Steve Rhoad's "mlite"

*

* This is a slightly modified version of Steve Rhoad's "mlite" simulator, which

* is part of his PLASMA project (original date: 1/31/01).

*

*-------------------------------------------------------------------------------

* Usage:

*     slite <code file name> <data file name>

*

* The program will allocate a chunk of RAM (MEM_SIZE bytes) and map it to

* address 0x00000000 of the simulated CPU.

* Then it will read the 'code file' (as a big-endian plain binary) onto address

* 0x0 of the simulated CPU memory, and 'data file' on address 0x10000.

* Finally, will reset the CPU and enter the interactive debugger.

*

* (Note that the above is only necessary if the system does not have caches,

* because of the Harvard architecture. With caches in place, program loading

* would be antirely conventional).

*

* A simulation log file will be dumped to file "sw_sim_log.txt". This log can be

* used to compare with an equivalent log dumped by the hardware simulation, as

* a simple way to validate the hardware for a given program. See the project

* readme files for details.

*

*-------------------------------------------------------------------------------

* KNOWN BUGS:

*

*-------------------------------------------------------------------------------

* @date 2011-jan-16

*

*-------------------------------------------------------------------------------

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

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

*

* IMPORTANT: Assumes host is little endian.

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

#include <stdio.h>

#include <stdlib.h>

#include <stdint.h>

#include <string.h>

#include <ctype.h>

#include <assert.h>

/** Set to !=0 to disable file logging (much faster simulation) */

#define FILE_LOGGING_DISABLED (0)

/** Define to enable cache simulation (unimplemented) */

//#define ENABLE_CACHE

/*---- Definition of simulated system parameters -----------------------------*/

#define VECTOR_RESET (0x00000000)

#define VECTOR_TRAP  (0x0000003c)

typedef struct s_block {

    uint32_t start;

    uint32_t size;

    uint8_t  *mem;

    char     *name;

} t_block;

/* Here's where we define the memory areas (blocks) of the system */

/* (make sure they don't overlap or the simulated program will crash) */

#define NUM_MEM_BLOCKS (2)

t_block default_blocks[NUM_MEM_BLOCKS] = {

    /* meant as bootstrap block, though it's read/write */

    {VECTOR_RESET,  0x00010000, NULL, "ROM"},

    /* main ram block  */

    {0x80000000,    0x00010000, NULL, "Data"}

};

#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)

/*---- OS-dependent support functions and definitions ------------------------*/

#ifndef WIN32

//Support for Linux

#define putch putchar

#include <termios.h>

#include <unistd.h>

void slite_sleep(unsigned int value){

    usleep(value * 1000);

}

int kbhit(void){

    struct termios oldt, newt;

    struct timeval tv;

    fd_set read_fd;

    tcgetattr(STDIN_FILENO, &oldt);

    newt = oldt;

    newt.c_lflag &= ~(ICANON | ECHO);

    tcsetattr(STDIN_FILENO, TCSANOW, &newt);

    tv.tv_sec=0;

    tv.tv_usec=0;

    FD_ZERO(&read_fd);

    FD_SET(0,&read_fd);

    if(select(1, &read_fd, NULL, NULL, &tv) == -1){

        return 0;

    }

    //tcsetattr(STDIN_FILENO, TCSANOW, &oldt);

    if(FD_ISSET(0,&read_fd)){

        return 1;

    }

    return 0;

}

int getch(void){

    struct termios oldt, newt;

    int ch;

    tcgetattr(STDIN_FILENO, &oldt);

    newt = oldt;

    newt.c_lflag &= ~(ICANON | ECHO);

    tcsetattr(STDIN_FILENO, TCSANOW, &newt);

    ch = getchar();

    //tcsetattr(STDIN_FILENO, TCSANOW, &oldt);

    return ch;

}

#else

//Support for Windows

#include <conio.h>

extern void __stdcall Sleep(unsigned long value);

void slite_sleep(unsigned int value){

    Sleep(value);

}

#endif

/*---- End of OS-dependent support functions and definitions -----------------*/

/*---- Hardware system parameters --------------------------------------------*/

/* Much of this is a remnant from Plasma's mlite and is  no longer used. */

/* FIXME Refactor HW system params */

#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

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

/* These are flags that will be used to notify the main cycle function of any

   failed assertions in its subfunctions. */

#define ASRT_UNALIGNED_READ         (1<<0)

#define ASRT_UNALIGNED_WRITE        (1<<1)

char *assertion_messages[2] = {

   "Unaligned read",

   "Unaligned write"

};

/** Length of debugging jump target queue */

#define TRACE_BUFFER_SIZE (32)

typedef struct s_trace {

   unsigned int buf[TRACE_BUFFER_SIZE];   /**< queue of last jump targets */

   unsigned int next;                     /**< internal queue head pointer */

   FILE *log;                             /**< text log file or NULL */

   int pr[32];                            /**< last value of register bank */

   int hi, lo, epc;                       /**< last value of internal regs */

} t_trace;

typedef struct s_state {

   unsigned failed_assertions;            /**< assertion bitmap */

   unsigned faulty_address;               /**< addr that failed assertion */

   int delay_slot;              /**< !=0 if prev. instruction was a branch */

   int r[32];

   int opcode;

   int pc, pc_next, epc;

   unsigned int hi;

   unsigned int lo;

   int status;

   unsigned cp0_cause;

   int userMode;

   int processId;

   int exceptionId;        /**< DEPRECATED, to be removed */

   int faultAddr;

   int irqStatus;

   int skip;

   t_trace t;

   //unsigned char *mem;

   t_block blocks[NUM_MEM_BLOCKS];

   int wakeup;

   int big_endian;

} t_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 int HWMemory[8];

/*---- Local function prototypes ---------------------------------------------*/

/* Debug and logging */

void init_trace_buffer(t_state *s, const char *log_file_name);

void close_trace_buffer(t_state *s);

void dump_trace_buffer(t_state *s);

void log_cycle(t_state *s);

void log_read(t_state *s, int full_address, int word_value, int size, int log);

void log_failed_assertions(t_state *s);

/* CPU model */

void free_cpu(t_state *s);

void init_cpu(t_state *s);

void reset_cpu(t_state *s);

/* Hardware simulation */

int mem_read(t_state *s, int size, unsigned int address, int log);

void mem_write(t_state *s, int size, unsigned address, unsigned value, int log);

void start_load(t_state *s, int rt, int data);

/*---- Local functions -------------------------------------------------------*/

/** Log to file a memory read operation (not including target reg change) */

void log_read(t_state *s, int full_address, int word_value, int size, int log){

   if(s->t.log!=NULL && log!=0){

      if(size==4){ size=0x04; }

      else if(size==2){ size=0x02; }

      else { size=0x01; }

      fprintf(s->t.log, "(%08X) [%08X] <**>=%08X RD\n",

              s->pc, full_address, /*size,*/ word_value);

   }

}

/** Read memory, optionally logging */

int mem_read(t_state *s, int size, unsigned int address, int log){

    unsigned int value=0, word_value=0, i, ptr;

    unsigned int full_address = address;

    s->irqStatus |= IRQ_UART_WRITE_AVAILABLE;

    switch(address){

    case UART_READ:

        word_value = 0x00000001;

        log_read(s, full_address, word_value, size, log);

        return word_value;

        /* FIXME Take input from text file */

        /*

        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:

       slite_sleep(10);

       return 0;

    case IRQ_STATUS:

       /*if(kbhit())

          s->irqStatus |= IRQ_UART_READ_AVAILABLE;

       return s->irqStatus;

       */

       /* FIXME Optionally simulate UART TX delay */

       word_value = 0x00000003; /* Ready to TX and RX */

       log_read(s, full_address, word_value, size, log);

       return word_value;

    case MMU_PROCESS_ID:

       return s->processId;

    case MMU_FAULT_ADDR:

       return s->faultAddr;

    }

    /* point ptr to the byte in the block, or NULL is the address is unmapped */

    ptr = 0;

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

        if(address >= s->blocks[i].start &&

          address < s->blocks[i].start + s->blocks[i].size){

            ptr = (unsigned)(s->blocks[i].mem) + address - s->blocks[i].start;

            break;

        }

    }

    if(!ptr){

        /* address out of mapped blocks: log and return zero */

        if(s->t.log!=NULL && log!=0){

            fprintf(s->t.log, "(%08X) [%08X] <**>=%08X RD UNMAPPED\n",

                s->pc, full_address, 0);

        }

        return 0;

    }

    /* get the whole word */

    word_value = *(int*)(ptr&0xfffffffc);

    if(s->big_endian){

        word_value = ntohl(word_value);

    }

    switch(size){

    case 4:

        if(address & 3){

            printf("Unaligned access PC=0x%x address=0x%x\n",

                (int)s->pc, (int)address);

        }

        if((address & 3) != 0){

            /* unaligned word, log fault */

            s->failed_assertions |= ASRT_UNALIGNED_READ;

            s->faulty_address = address;

            address = address & 0xfffffffc;

        }

        value = *(int*)ptr;

        if(s->big_endian){

            value = ntohl(value);

        }

        break;

    case 2:

        if((address & 1) != 0){

            /* unaligned halfword, log fault */

            s->failed_assertions |= ASRT_UNALIGNED_READ;

            s->faulty_address = address;

            address = address & 0xfffffffe;

        }

        value = *(unsigned short*)ptr;

        if(s->big_endian){

            value = ntohs((unsigned short)value);

        }

        break;

    case 1:

        value = *(unsigned char*)ptr;

        break;

    default:

        /* FIXME this is a bug, should quit */

        printf("ERROR");

    }

    log_read(s, full_address, word_value, size, log);

    return(value);

}

/** Write memory */

void mem_write(t_state *s, int size, unsigned address, unsigned value, int log){

    unsigned int i, ptr, mask, dvalue, b0, b1, b2, b3;

    if(s->t.log!=NULL){

        b0 = value & 0x000000ff;

        b1 = value & 0x0000ff00;

        b2 = value & 0x00ff0000;

        b3 = value & 0xff000000;

        switch(size){

        case 4:  mask = 0x0f;

            dvalue = value;

            break;

        case 2:

            if((address&0x2)==0){

                mask = 0xc;

                dvalue = b1<<16 | b0<<16;

            }

            else{

               mask = 0x3;

               dvalue = b1 | b0;

            }

            break;

        case 1:

            switch(address%4){

            case 0 : mask = 0x8;

                dvalue = b0<<24;

                break;

            case 1 : mask = 0x4;

                dvalue = b0<<16;

                break;

            case 2 : mask = 0x2;

                dvalue = b0<<8;

                break;

            case 3 : mask = 0x1;

                dvalue = b0;

                break;

            }

            break;

        default:

            printf("BUG: mem write size invalid (%08x)\n", s->pc);

            exit(2);

        }

        fprintf(s->t.log, "(%08X) [%08X] |%02X|=%08X WR\n",

                s->pc, address, mask, dvalue);

    }

    switch(address){

    case UART_WRITE:

        putch(value);

        fflush(stdout);

        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;

    }

    //ptr = (unsigned int)s->mem + (address % MEM_SIZE);

    if(address >= 0x80000000){

        ptr = 1;

    }

    ptr = 0;

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

        if(address >= s->blocks[i].start &&

          address < s->blocks[i].start + s->blocks[i].size){

            ptr = (unsigned)(s->blocks[i].mem) + address - s->blocks[i].start;

            break;

        }

    }

    if(!ptr){

        /* address out of mapped blocks: log and return zero */

        if(s->t.log!=NULL && log!=0){

            fprintf(s->t.log, "(%08X) [%08X] |%02X|=%08X WR UNMAPPED\n",

                s->pc, address, mask, dvalue);

        }

        return;

    }

    switch(size){

    case 4:

        if((address & 3) != 0){

            /* unaligned word, log fault */

            s->failed_assertions |= ASRT_UNALIGNED_WRITE;

            s->faulty_address = address;

            address = address & (~0x03);

        }

        if(s->big_endian){

            value = htonl(value);

        }

        *(int*)ptr = value;

        break;

    case 2:

        if((address & 1) != 0){

            /* unaligned halfword, log fault */

            s->failed_assertions |= ASRT_UNALIGNED_WRITE;

            s->faulty_address = address;

            address = address & (~0x01);

        }

        if(s->big_endian){

            value = htons((unsigned short)value);

        }

        *(short*)ptr = (unsigned short)value;

        break;

    case 1:

        *(char*)ptr = (unsigned char)value;

        break;

    default:

        /* FIXME this is a bug, should quit */

        printf("ERROR");

    }

}

/*---- Optional MMU and cache implementation ---------------------------------*/

/*

   The actual core does not have a cache so all of the original Plasma mlite.c

   code for cache simulation has been removed.

*/

/*---- End optional cache implementation -------------------------------------*/

/** Simulates MIPS-I multiplier unsigned behavior*/

void mult_big(unsigned int a,

              unsigned int b,

              unsigned int *hi,

              unsigned int *lo){

    unsigned int ahi, alo, bhi, blo;

    unsigned int c0, c1, c2;

    unsigned int 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;

}

/** Simulates MIPS-I multiplier signed behavior*/

void mult_big_signed(int a,

                     int b,

                     unsigned int *hi,

                     unsigned int *lo){

    int64_t xa, xb, xr, temp;

    int32_t rh, rl;

    xa = a;

    xb = b;

    xr = xa * xb;

    temp = (xr >> 32) & 0xffffffff;

    rh = temp;

    temp = (xr >> 0) & 0xffffffff;

    rl = temp;

    *hi = rh;

    *lo = rl;

}

/** Load data from memory (used to simulate load delay slots) */

void start_load(t_state *s, int rt, int data){

    /* load delay slot not simulated */

    s->r[rt] = data;

}

/** Execute one cycle of the CPU (including any interlock stall cycles) */

void cycle(t_state *s, int show_mode){

    unsigned int opcode;

    int delay_slot = 0; /* 1 of this instruction is a branch */

    unsigned int op, rs, rt, rd, re, func, imm, target;

    int trap_cause = 0;

    int imm_shift, branch=0, lbranch=2, skip2=0;

    int *r=s->r;

    unsigned int *u=(unsigned int*)s->r;

    unsigned int ptr, epc, rSave;

    if(!show_mode){

        /* if we're NOT showing output to console, log state of CPU to file */

        log_cycle(s);

    }

    opcode = mem_read(s, 4, s->pc, 0);

    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 = (((int)(short)imm) << 2) - 4;

    target = (opcode << 6) >> 4;

    ptr = (short)imm + r[rs];

    r[0] = 0;

    /* if we are priting state to console, do it now */

    if(show_mode){

        printf("%8.8x %8.8x ", 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("$%2.2d $%2.2d $%2.2d $%2.2d ", rs, rt, rd, re);

        printf("%4.4x", 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 we're just showing state to console, quit and don't run instruction */