/*
 * Part of Scheme 48 1.9.  See file COPYING for notices and license.
 *
 * Authors: Richard Kelsey, Jonathan Rees, Mike Sperber
 */

/* Implementation of the vm-extension opcode.  This is completely
   optional; nothing in the standard system uses these features.

   The vm-extension opcode is being phased out.  New code should use the
   external-call opcode to call C procedures.
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <signal.h>
#include <errno.h>

#include "scheme48.h"

#define GREATEST_FIXNUM_VALUE S48_MAX_FIXNUM_VALUE
#define LEAST_FIXNUM_VALUE S48_MIN_FIXNUM_VALUE
#define CHANNEL_INDEX(x) EXTRACT_FIXNUM(STOB_REF(x, 1))
#define FOR_INPUT 1
#define FOR_OUTPUT 2

typedef struct {
  char b[sizeof(double)];
} unaligned_double;

typedef union {
  double f;
  unaligned_double b;
} float_or_bytes;

extern long s48_Sextension_valueS;  /* how values are returned */

/* return status values */
#define EXT_ST_OKAY 0
#define EXT_ST_EXCEPTION 1

#define EXT_RETURN(value) {s48_Sextension_valueS = (value); return EXT_ST_OKAY; }
#define EXT_EXCEPTION     return EXT_ST_EXCEPTION

/******************************************/

s48_value
s48_extended_vm (long key, s48_value value)
{
  double x, y;

  switch (key) {

    /* Cases 0 through 19 are reserved for the mobot system. */

  case 0:			/* read jumpers on 68000 board */
    EXT_RETURN(S48_UNSAFE_ENTER_FIXNUM(0));

  /* Floating point */

#define FLOP 100
#define FLOP2(i) case FLOP+(i): \
		   if (!S48_STOB_P(value) || S48_STOB_DESCRIPTOR_LENGTH(value) != 2) \
		     EXT_EXCEPTION;
#define FLOP3(i) case FLOP+(i): \
		   if (!S48_STOB_P(value) || S48_STOB_DESCRIPTOR_LENGTH(value) != 3) \
		     EXT_EXCEPTION;

#define get_arg(args,i) S48_STOB_REF(args,(i))
#define get_string_arg(args,i) (S48_UNSAFE_EXTRACT_STRING(get_arg(args,i)))

#define get_float_arg(args, i, var) EXTRACT_FLOAT(get_arg(args, i), var)
#define set_float_arg(args, i, val) SET_FLOAT(get_arg(args, i), val)

#define EXTRACT_FLOAT(stob, var) \
  { s48_value temp_ = (stob); \
    float_or_bytes loser_; \
    if (!S48_STOB_P(temp_)) EXT_EXCEPTION; \
    loser_.b = *(unaligned_double*)(&S48_STOB_REF(temp_, 0)); \
    (var) = loser_.f; }

#define SET_FLOAT(stob, val) \
  { s48_value temp_ = (stob); \
    float_or_bytes loser_; \
    if (!S48_STOB_P(temp_)) EXT_EXCEPTION; \
    loser_.f = (double)(val); \
    *(unaligned_double*)(&S48_STOB_REF(temp_, 0)) = loser_.b; }

  FLOP2(0) {			/* fixnum->float */
    s48_value arg = get_arg(value, 0);
    if (!S48_FIXNUM_P(arg)) EXT_RETURN(S48_FALSE);
    set_float_arg(value, 1, S48_UNSAFE_EXTRACT_FIXNUM(arg));
    EXT_RETURN(S48_TRUE);}
  FLOP2(1) {			/* string->float */
    static char* buf = NULL;
    static size_t max_size = 0;
    size_t len = s48_string_length(get_arg(value, 0));
    double retval;
    extern double ps_pos_infinity(void), ps_neg_infinity(void), ps_not_a_number(void);
    if (len + 1 > max_size)
      {
	max_size = ((len > 40) ? (len + 1) : 41);
	buf = realloc(buf, max_size);
	if (buf == NULL)
	  EXT_RETURN(S48_FALSE);
      }
    s48_copy_string_to_latin_1(get_arg(value, 0), buf);
    buf[len] = '\0';
    if (buf[0] == '+')
      {
	if (!strcmp(buf, "+inf.0"))
	  retval = ps_pos_infinity();
	else if (!strcmp(buf, "+nan.0"))
	  retval = ps_not_a_number();
	else
	  retval = atof(buf);
      }
    else if (buf[0] == '-')
      {
	if (!strcmp(buf, "-inf.0"))
	  retval = ps_neg_infinity();
	else if (!strcmp(buf, "-nan.0"))
	  retval = ps_not_a_number();
	else
	  retval = atof(buf);
      }
    else
      retval = atof(buf);
	
    set_float_arg(value, 1, retval);
    EXT_RETURN(get_arg(value, 1));
  }
  FLOP2(2) {			/* float->string */
    extern size_t s48_double_to_string(char *buf, double v);
    static char buf[40];
    int i;
    size_t len;
    get_float_arg(value, 0, x);
    len = s48_double_to_string(buf, x);
    s48_copy_latin_1_to_string_n(buf, len, get_arg(value,1));
    EXT_RETURN(S48_UNSAFE_ENTER_FIXNUM(len));
  }
  
    /* exp log sin cos tan asin acos atan1 atan2 sqrt */

  FLOP2(3) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, exp(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(4) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, log(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(5) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, sin(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(6) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, cos(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(7) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, tan(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(8) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, asin(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(9) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, acos(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(10) {			/* atan 1 */
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, atan(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP3(11) {			/* atan 2 */
    get_float_arg(value, 0, y);
    get_float_arg(value, 1, x);
    set_float_arg(value, 2, atan2(y, x));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP2(12) {
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, sqrt(x));
    EXT_RETURN(S48_UNSPECIFIC);}

  FLOP2(13) {			/* floor */
    get_float_arg(value, 0, x);
    set_float_arg(value, 1, floor(x));
    EXT_RETURN(S48_UNSPECIFIC);}
  case FLOP+14: {		/* integer? */
    EXTRACT_FLOAT(value, x);
    EXT_RETURN(S48_ENTER_BOOLEAN(fmod(x, 1.0) == 0.0)); }
  case FLOP+15: {		/* float->fixnum */
    EXTRACT_FLOAT(value, x);
    if (x <= (double)GREATEST_FIXNUM_VALUE
	&& x >= (double)LEAST_FIXNUM_VALUE)
      {
      EXT_RETURN(S48_UNSAFE_ENTER_FIXNUM((long)x)); }
    else
      EXT_RETURN(S48_FALSE);}
  FLOP3(16) {			/* quotient */
    double z;
    get_float_arg(value, 0, x);
    get_float_arg(value, 1, y);
    if (fmod(x, 1.0) != 0.0 || fmod(y, 1.0) != 0.0) EXT_EXCEPTION;
    if (y == 0.0) EXT_EXCEPTION;
    z = x / y;
    set_float_arg(value, 2, z < 0.0 ? ceil(z) : floor(z));
    EXT_RETURN(S48_UNSPECIFIC);}
  FLOP3(17) {			/* remainder */
    get_float_arg(value, 0, x);
    get_float_arg(value, 1, y);
    if (fmod(x, 1.0) != 0.0 || fmod(y, 1.0) != 0.0) EXT_EXCEPTION;
    if (y == 0.0) EXT_EXCEPTION;

    /* "fmod(double x, double y) returns the floating-point remainder
       (f) of the division of x by y, where f has the same sign as x,
       such that x=iy+f for some integer i, and |f| < |y|." */

    set_float_arg(value, 2, fmod(x, y));
    EXT_RETURN(S48_UNSPECIFIC);}

  default:
    EXT_EXCEPTION;
  }
}

