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Tentatively manually encoding non-finite f16 values.

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Issue #988.
This commit is contained in:
Alex Shinn 2024-06-02 22:31:25 +09:00
parent 3be1603f45
commit d4028f953b
2 changed files with 19 additions and 8 deletions
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6
lib/srfi/160/mini-test.sld
View file

@ -1,6 +1,6 @@
(define-library (srfi 160 mini-test)
(import (scheme base)
(import (scheme base) (scheme inexact)
(srfi 160 base) (srfi 160 f8) (srfi 160 f16)
(chibi test))
(export run-tests)
@ -83,6 +83,10 @@
(vector->f16vector '#(0 1 2 3) 1 3))
(test '#(1.0 2.0)
(f16vector->vector '#f16(0 1 2 3) 1 3))
(test '(-inf.0 -1.0 -0.0 0.0 1.0 +inf.0)
(f16vector->list
'#f16(-inf.0 -1.0 -0.0 0.0 1.0 +inf.0)))
(test-assert (nan? (f16vector-ref '#f16(+nan.0) 0)))
)
(test-end))))

15
sexp.c
View file

@ -3206,15 +3206,22 @@ static float int_as_float(const unsigned int n) {
/* https://arxiv.org/abs/2112.08926 */
double sexp_half_to_double(unsigned short x) {
unsigned int e = (x&0x7C00)>>10,
m = (x&0x03FF)<<13,
unsigned int e, m, v;
if (x == 31744) return INFINITY;
if (x == 32767) return NAN;
if (x == 64512) return -INFINITY;
e = (x&0x7C00)>>10;
m = (x&0x03FF)<<13;
v = float_as_int((float)m)>>23;
return int_as_float((x&0x8000)<<16 | (e!=0)*((e+112)<<23|m) | ((e==0)&(m!=0))*((v-37)<<23|((m<<(150-v))&0x007FE000)));
}
unsigned short sexp_double_to_half(double x) {
unsigned int b = float_as_int(x)+0x00001000,
e = (b&0x7F800000)>>23,
unsigned int b, e, m;
if (isnan(x)) return 32767;
if (isinf(x)) return x < 0 ? 64512 : 31744;
b = float_as_int(x)+0x00001000;
e = (b&0x7F800000)>>23;
m = b&0x007FFFFF;
return (b&0x80000000)>>16 | (e>112)*((((e-112)<<10)&0x7C00)|m>>13) | ((e<113)&(e>101))*((((0x007FF000+m)>>(125-e))+1)>>1) | (e>143)*0x7FFF;
}