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Add simple example based on original C program built by David Harris for OSU who want to see easy way to convert FP numbers

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James E. Stine 2023-04-12 17:20:11 -05:00
parent dee4d49e42
commit 4503ad4c87
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examples/fp/softfloat_demo/softfloat_demo2.c Normal file
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//
// softfloat_div.c
// james.stine@okstate.edu 12 April 2023
//
// Demonstrate using SoftFloat to compute 754 fp divide, then print results
// (adapted from original C built by David Harris)
//
#include <stdio.h>
#include <stdint.h>
#include "softfloat.h"
#include "softfloat_types.h"
typedef union sp {
uint32_t v;
unsigned short x[2];
float f;
} sp;
void printF32 (char *msg, float32_t f) {
sp conv;
int i, j;
conv.v = f.v; // use union to convert between hexadecimal and floating-point views
printf("%s: ", msg); // print out nicely
printf("0x%04x_%04x = %1.15g\n", (conv.v >> 16),(conv.v & 0xFFFF), conv.f);
}
void printFlags(void) {
int NX = softfloat_exceptionFlags % 2;
int UF = (softfloat_exceptionFlags >> 1) % 2;
int OF = (softfloat_exceptionFlags >> 2) % 2;
int DZ = (softfloat_exceptionFlags >> 3) % 2;
int NV = (softfloat_exceptionFlags >> 4) % 2;
printf ("Flags: Inexact %d Underflow %d Overflow %d DivideZero %d Invalid %d\n",
NX, UF, OF, DZ, NV);
}
void softfloatInit(void) {
// RNE: softfloat_round_near_even
// RZ: softfloat_round_minMag
// RU: softfloat_round_max
// RD: softfloat_round_min
// RM: softfloat_round_near_maxMag
softfloat_roundingMode = softfloat_round_near_even;
softfloat_exceptionFlags = 0; // clear exceptions
softfloat_detectTininess = softfloat_tininess_afterRounding; // RISC-V behavior for tininess
}
int main() {
// float32_t is typedef in SoftFloat
float32_t x, y, r1, r2;
sp convx, convy;
// Choose two random values
convx.f = 1.30308703073;
convy.f = 1.903038030370;
// Convert to SoftFloat format
x.v = (convx.x[1] << 16) + convx.x[0];
y.v = (convy.x[1] << 16) + convy.x[0];
printf("Example using SoftFloat\n");
softfloatInit();
r1 = f32_div(x, y);
printf("-------\n");
printF32("X", x);
printF32("Y", y);
printF32("result = X/Y", r1);
printFlags();
r2 = f32_sqrt(x);
printf("-------\n");
printF32("X", x);
printF32("result = sqrt(X)", r2);
printFlags();
}