retroforth/vm/nga-c/dev-floatingpoint.c

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/*---------------------------------------------------------------------
Floating Point
---------------------------------------------------------------------*/
/*---------------------------------------------------------------------
I have a stack of floating point values ("floats") and a stack
pointer (`fsp`).
---------------------------------------------------------------------*/
double Floats[256];
CELL fsp;
double AFloats[256];
CELL afsp;
/*---------------------------------------------------------------------
The first two functions push a float to the stack and pop a value off
the stack.
---------------------------------------------------------------------*/
void float_guard() {
#ifndef NOCHECKS
if (fsp < 0 || fsp > 255) {
printf("\nERROR (nga/float_guard): Float Stack Limits Exceeded!\n");
printf("At %lld, fsp = %lld\n", (long long)ip, (long long)fsp);
exit(1);
}
if (afsp < 0 || afsp > 255) {
printf("\nERROR (nga/float_guard): Alternate Float Stack Limits Exceeded!\n");
printf("At %lld, afsp = %lld\n", (long long)ip, (long long)afsp);
exit(1);
}
#endif
}
void float_push(double value) {
fsp++;
float_guard();
Floats[fsp] = value;
}
double float_pop() {
fsp--;
float_guard();
return Floats[fsp + 1];
}
void float_to_alt() {
afsp++;
float_guard();
AFloats[afsp] = float_pop();
}
void float_from_alt() {
float_push(AFloats[afsp]);
afsp--;
float_guard();
}
/*---------------------------------------------------------------------
RETRO operates on 32-bit signed integer values. This function just
pops a number from the data stack, casts it to a float, and pushes it
to the float stack.
---------------------------------------------------------------------*/
void float_from_number() {
float_push((double)stack_pop());
}
/*---------------------------------------------------------------------
To get a float from a string in the image, I provide this function.
I cheat: using `atof()` takes care of the details, so I don't have
to.
---------------------------------------------------------------------*/
void float_from_string() {
float_push(atof(string_extract(stack_pop())));
}
/*---------------------------------------------------------------------
Converting a floating point into a string is slightly more work. Here
I pass it off to `snprintf()` to deal with.
---------------------------------------------------------------------*/
void float_to_string() {
snprintf(string_data, 8192, "%f", float_pop());
string_inject(string_data, stack_pop());
}
/*---------------------------------------------------------------------
Converting a floating point back into a standard number requires a
little care due to the signed nature. This makes adjustments for the
max & min value, and then casts (rounding) the float back to a normal
number.
---------------------------------------------------------------------*/
void float_to_number() {
double a = float_pop();
if (a > 2147483647)
a = 2147483647;
if (a < -2147483648)
a = -2147483648;
stack_push((CELL)round(a));
}
/*---------------------------------------------------------------------
Now I get to define a bunch of functions that operate on floats.
These provide the basic math, and wrappers around functionality in
libm.
---------------------------------------------------------------------*/
void float_add() {
double a = float_pop();
double b = float_pop();
float_push(a+b);
}
void float_sub() {
double a = float_pop();
double b = float_pop();
float_push(b-a);
}
void float_mul() {
double a = float_pop();
double b = float_pop();
float_push(a*b);
}
void float_div() {
double a = float_pop();
double b = float_pop();
float_push(b/a);
}
void float_floor() {
float_push(floor(float_pop()));
}
void float_ceil() {
float_push(ceil(float_pop()));
}
void float_eq() {
double a = float_pop();
double b = float_pop();
if (a == b)
stack_push(-1);
else
stack_push(0);
}
void float_neq() {
double a = float_pop();
double b = float_pop();
if (a != b)
stack_push(-1);
else
stack_push(0);
}
void float_lt() {
double a = float_pop();
double b = float_pop();
if (b < a)
stack_push(-1);
else
stack_push(0);
}
void float_gt() {
double a = float_pop();
double b = float_pop();
if (b > a)
stack_push(-1);
else
stack_push(0);
}
void float_depth() {
stack_push(fsp);
}
void float_adepth() {
stack_push(afsp);
}
void float_dup() {
double a = float_pop();
float_push(a);
float_push(a);
}
void float_drop() {
float_pop();
}
void float_swap() {
double a = float_pop();
double b = float_pop();
float_push(a);
float_push(b);
}
void float_log() {
double a = float_pop();
double b = float_pop();
float_push(log(b) / log(a));
}
void float_sqrt() {
float_push(sqrt(float_pop()));
}
void float_pow() {
double a = float_pop();
double b = float_pop();
float_push(pow(b, a));
}
void float_sin() {
float_push(sin(float_pop()));
}
void float_cos() {
float_push(cos(float_pop()));
}
void float_tan() {
float_push(tan(float_pop()));
}
void float_asin() {
float_push(asin(float_pop()));
}
void float_acos() {
float_push(acos(float_pop()));
}
void float_atan() {
float_push(atan(float_pop()));
}
/*---------------------------------------------------------------------
With this finally done, I implement the FPU instructions.
---------------------------------------------------------------------*/
Handler FloatHandlers[] = {
float_from_number, float_from_string, float_to_number, float_to_string,
float_add, float_sub, float_mul, float_div,
float_floor, float_ceil, float_sqrt, float_eq,
float_neq, float_lt, float_gt, float_depth,
float_dup, float_drop, float_swap, float_log,
float_pow, float_sin, float_tan, float_cos,
float_asin, float_acos, float_atan, float_to_alt,
float_from_alt, float_adepth,
};
void io_floatingpoint_query() {
stack_push(1);
stack_push(2);
}
void io_floatingpoint_handler() {
FloatHandlers[stack_pop()]();
}