make casting between __float128 and long double explicit

1 files changed, 12 insertions, 7 deletions

diff --git a/src/bigfloat.cpp b/src/bigfloat.cpp
index 8e19f0a031..ba09945824 100644
--- a/src/bigfloat.cpp
+++ b/src/bigfloat.cpp
@@ -5,6 +5,11 @@
  * See http://opensource.org/licenses/MIT
  */
 
+// TODO in this file we cast between __float128 and long double
+// and lose precision. for now this is going to be a bug in
+// the compiler because I don't want to add a dependency on libquadmath.
+// when we self host we can use zig's f128 and the problem is fixed.
+
 #include "bigfloat.hpp"
 #include "bigint.hpp"
 #include "buffer.hpp"
@@ -46,7 +51,7 @@ int bigfloat_init_buf_base10(BigFloat *dest, const uint8_t *buf_ptr, size_t buf_
     char *str_begin = (char *)buf_ptr;
     char *str_end;
     errno = 0;
-    dest->value = strtold(str_begin, &str_end);
+    dest->value = (__float128)strtold(str_begin, &str_end);
     if (errno) {
         return ErrorOverflow;
     }
@@ -77,22 +82,22 @@ void bigfloat_div(BigFloat *dest, const BigFloat *op1, const BigFloat *op2) {
 void bigfloat_div_trunc(BigFloat *dest, const BigFloat *op1, const BigFloat *op2) {
     dest->value = op1->value / op2->value;
     if (dest->value >= 0.0) {
-        dest->value = floorl(dest->value);
+        dest->value = (__float128)floorl((long double)dest->value);
     } else {
-        dest->value = ceill(dest->value);
+        dest->value = (__float128)ceill((long double)dest->value);
     }
 }
 
 void bigfloat_div_floor(BigFloat *dest, const BigFloat *op1, const BigFloat *op2) {
-    dest->value = floorl(op1->value / op2->value);
+    dest->value = (__float128)floorl((long double)(op1->value / op2->value));
 }
 
 void bigfloat_rem(BigFloat *dest, const BigFloat *op1, const BigFloat *op2) {
-    dest->value = fmodl(op1->value, op2->value);
+    dest->value = (__float128)fmodl((long double)op1->value, (long double)op2->value);
 }
 
 void bigfloat_mod(BigFloat *dest, const BigFloat *op1, const BigFloat *op2) {
-    dest->value = fmodl(fmodl(op1->value, op2->value) + op2->value, op2->value);
+    dest->value = (__float128)fmodl(fmodl((long double)op1->value, (long double)op2->value) + (long double)op2->value, (long double)op2->value);
 }
 
 void bigfloat_write_buf(Buf *buf, const BigFloat *op) {
@@ -159,5 +164,5 @@ Cmp bigfloat_cmp_zero(const BigFloat *bigfloat) {
 }
 
 bool bigfloat_has_fraction(const BigFloat *bigfloat) {
-    return floorl(bigfloat->value) != bigfloat->value;
+    return ((__float128)floorl((long double)bigfloat->value)) != bigfloat->value;
 }