retroforth/interfaces/io/io_floatingpoint.c

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/* RETRO ------------------------------------------------------
A personal, minimalistic forth
Copyright (c) 2016 - 2019 Charles Childers
---------------------------------------------------------- */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
#include <sys/wait.h>
#include <signal.h>
typedef void (*Handler)(void);
/*---------------------------------------------------------------------
First, a few things that relate to the Nga virtual machine that RETRO
runs on.
---------------------------------------------------------------------*/
#define CELL int32_t /* Cell size (32 bit, signed integer */
#define IMAGE_SIZE 524288 * 48 /* Amount of RAM. 12MiB by default. */
#define ADDRESSES 2048 /* Depth of address stack */
#define STACK_DEPTH 512 /* Depth of data stack */
extern CELL sp, rp, ip; /* Stack & instruction pointers */
extern CELL data[STACK_DEPTH]; /* The data stack */
extern CELL address[ADDRESSES]; /* The address stack */
extern CELL memory[IMAGE_SIZE + 1]; /* The memory for the image */
extern char string_data[];
#define TOS data[sp] /* Shortcut for top item on stack */
#define NOS data[sp-1] /* Shortcut for second item on stack */
#define TORS address[rp] /* Shortcut for top item on address stack */
/*---------------------------------------------------------------------
Function prototypes.
---------------------------------------------------------------------*/
CELL stack_pop();
void stack_push(CELL value);
char *string_extract(CELL at);
CELL string_inject(char *str, CELL buffer);
/*---------------------------------------------------------------------
I have a stack of floating point values ("floats") and a stack
pointer (`fsp`).
---------------------------------------------------------------------*/
double Floats[8192];
CELL fsp;
double AFloats[8192];
CELL afsp;
/*---------------------------------------------------------------------
The first two functions push a float to the stack and pop a value off
the stack.
---------------------------------------------------------------------*/
void float_push(double value) {
fsp++;
Floats[fsp] = value;
}
double float_pop() {
fsp--;
return Floats[fsp + 1];
}
void float_to_alt() {
afsp++;
AFloats[afsp] = float_pop();
}
void float_from_alt() {
float_push(AFloats[afsp]);
afsp--;
}
/*---------------------------------------------------------------------
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()]();
}