#!/usr/bin/env python3
# n808 VM reference implementation in Python 3/MicroPython
# Supports the entire n808 spec
# See README.md for all documentation
# Created by Luxferre in 2025, released into public domain

import sys, math, random, re

advterm = False
try:
    import tty, termios # for the character input port
    advterm = True
except:
    pass

MEMLIMIT:int = 128
PMEM = [0 for i in range(0, MEMLIMIT)]   # program memory
DMEM = [0.0 for i in range(0, MEMLIMIT)] # data memory

# port I/O function
def portio(port:int, data:float):
    if port == 0: print(data) # standard numeric output
    elif port == 1: # standard numeric input
        try: data = float(input())
        except ValueError: data = 0
    elif port == 2: # character output
        sys.stdout.write(chr(int(data)&255))
        sys.stdout.flush()
    elif port == 3: # character input
        ch = '\0'
        if advterm: # normal OS with termios
            fd = sys.stdin.fileno()
            old_settings = termios.tcgetattr(fd)
            try:
                tty.setraw(fd)
                ch = sys.stdin.read(1)
            finally:
                termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
        else: # crippled OS without termios
            ch = sys.stdin.read(1)
        data = float(ord(ch))
    return data

# main instruction execution logic
def iexec(lno:int):
    global PMEM, DMEM
    data_override = 0
    while True: # decode and execute the current instruction
        cmd = (PMEM[lno] >> 21) & 7  # command opcode
        p1 = (int(v1) if data_override else (PMEM[lno] >> 14)) & 127 # parameter 1
        p2 = (int(v2) if data_override else (PMEM[lno] >> 7)) & 127  # parameter 2
        p3 = (int(v3) if data_override else PMEM[lno]) & 127         # parameter 3
        DMEM[0] = data_override = 0 # enforce the 0 at the location 0
        DMEM[127] = 1               # enforce the 1 at the location 127
        DMEM[126] = -1              # enforce the -1 at the location 126
        v1 = DMEM[p1]; v2 = DMEM[p2]; v3 = DMEM[p3] # prefetch the values
        if cmd == 1:                                                          # JMP
            if p1 == 14: DMEM[125] = lno + 1
            if (v2 == 0 and p1 == 0) or (v2 > 0 and p1 == 1) or (v2 < 0 and p1 == 2) \
            or (v2 >= 0 and p1 == 3) or (v2 <= 0 and p1 == 4) or (v2 != 0 and p1 == 5) \
            or p1 == 6 or p1 == 14: lno = p3 - 1
            elif (v2 == 0 and p1 == 7) or (v2 > 0 and p1 == 8) or (v2 < 0 and p1 == 9) \
            or (v2 >= 0 and p1 == 10) or (v2 <= 0 and p1 == 11) or (v2 != 0 and p1 == 12) \
            or p1 == 13: lno = int(v3) - 1
        elif cmd == 2: data_override = 1                                      # IAT
        elif cmd == 3:                                                        # INO
            for i in range(p2,p3+1): DMEM[i] = portio(p1, DMEM[i])
        elif cmd == 4:                                                        # CPY
            if p1 == 0: DMEM[p3] = p2
            elif p1 == 1: DMEM[p3] = v2
            elif p1 == 2: DMEM[int(v3)] = p2
            elif p1 == 3: DMEM[int(v3)] = v2
            elif p1 == 4: DMEM[int(v3)] = DMEM[int(v2)]
        elif cmd == 5: DMEM[p3] = p1 * 100 + p2 + v3 / 100.0                  # SET
        elif cmd == 6:                                                        # MAT
            if p1 == 0: DMEM[p3] = v2 + v3
            elif p1 == 1: DMEM[p3] = v2 - v3
            elif p1 == 2: DMEM[p3] = v2 * v3
            elif p1 == 3: DMEM[p3] = 0 if v3 == 0 else (v2 / v3)
            elif p1 == 4: DMEM[p3] = math.floor(v2) if v3 == 0 else (v2 % v3)
            elif p1 == 5: DMEM[p3] = math.fabs(v2)
            elif p1 == 6: DMEM[p3] = math.sqrt(math.fabs(v2))
            elif p1 == 7: DMEM[p3] = math.exp(v2)
            elif p1 == 8: DMEM[p3] = 0 if v2 == 0 else math.log(math.fabs(v2))
            elif p1 == 9: DMEM[p3] = math.sin(v2)
            elif p1 == 10: DMEM[p3] = math.cos(v2)
            elif p1 == 11: DMEM[p3] = math.atan(v2)
        elif cmd == 7: DMEM[p3] = float(random.randint(int(v1), int(v2)))     # RND
        lno += 1 # increment the program counter
        if lno >= MEMLIMIT: break

# interactive mode entry function
def intermode(cmd:int, p1:int, p2:int):
  if cmd == 0 and p1 < MEMLIMIT: iexec(p1)            # run from the step
  elif cmd == 1 and p1 < MEMLIMIT: PMEM[p1] = p2      # enter the instruction into PMEM
  elif cmd == 2 and p1 < MEMLIMIT and p2 < MEMLIMIT:  # clear instructions
    for cmd in range(p1, p2+1): PMEM[cmd] = 0
  elif cmd == 3 and p1 < MEMLIMIT and p2 < MEMLIMIT:  # clear data
    for cmd in range(p1, p2+1): DMEM[cmd] = 0.0
  elif cmd == 4:
    print("Bye!")
    sys.exit(0)

# main REPL environment
if __name__ == '__main__':
    vreg = re.compile(r'[^-\d]+')
    if len(sys.argv) > 1: # preload the file contents
        fc = ''
        try:
            fd = open(sys.argv[1], 'r')
            fc = fd.read()
            close(fd)
        except:
            pass
        instr = [] # current instruction cache
        iindex = 0
        for instrpart in vreg.split(fc):
            if len(instrpart) > 0:
                intermode(1, iindex, int(instrpart))
                instr.append(int(instrpart))
                iindex += 1
    instr = [] # current instruction cache
    while True: # main interactive loop
        rinput = input('> ')
        if len(rinput) > 0:
            for v in vreg.split(rinput): # loop over the current input
                if len(v) > 0:
                    instr.append(v)
                if len(instr) == 3: # full instruction registered
                    intermode(int(instr[0]), int(instr[1]), int(instr[2]))
                    instr = []