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numeric.c: refactor integer bit shift operations.

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This commit is contained in:
Yukihiro "Matz" Matsumoto
2021-08-02 08:53:14 +09:00
parent 907df715ef
commit a9d721ea8f
1 changed files with 28 additions and 29 deletions
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src/numeric.c
+28 -29
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@@ -1306,37 +1306,37 @@ int_xor(mrb_state *mrb, mrb_value x)
#define NUMERIC_SHIFT_WIDTH_MAX (MRB_INT_BIT-1)
static mrb_value
lshift(mrb_state *mrb, mrb_int val, mrb_int width)
mrb_bool
mrb_num_shift(mrb_state *mrb, mrb_int val, mrb_int width, mrb_int *num)
{
mrb_assert(width >= 0);
if (val > 0) {
if (width < 0) { /* rshift */
if (width == MRB_INT_MIN || -width >= NUMERIC_SHIFT_WIDTH_MAX) {
if (val < 0) {
*num = -1;
}
else {
*num = 0;
}
}
else {
*num = val >> -width;
}
}
else if (val > 0) {
if ((width > NUMERIC_SHIFT_WIDTH_MAX) ||
(val > (MRB_INT_MAX >> width))) {
int_overflow(mrb, "bit shift");
return FALSE;
}
return mrb_int_value(mrb, val << width);
*num = val << width;
}
else {
if ((width > NUMERIC_SHIFT_WIDTH_MAX) ||
(val <= (MRB_INT_MIN >> width))) {
int_overflow(mrb, "bit shift");
return FALSE;
}
return mrb_int_value(mrb, (val * ((mrb_int)1 << width)));
*num = val * ((mrb_int)1 << width);
}
}
static mrb_value
rshift(mrb_state *mrb, mrb_int val, mrb_int width)
{
mrb_assert(width >= 0);
if (width >= NUMERIC_SHIFT_WIDTH_MAX) {
if (val < 0) {
return mrb_fixnum_value(-1);
}
return mrb_fixnum_value(0);
}
return mrb_int_value(mrb, val >> width);
return TRUE;
}
/* 15.2.8.3.12 */
@@ -1358,11 +1358,10 @@ int_lshift(mrb_state *mrb, mrb_value x)
}
val = mrb_integer(x);
if (val == 0) return x;
if (width < 0) {
if (width == MRB_INT_MIN) return rshift(mrb, val, MRB_INT_BIT);
return rshift(mrb, val, -width);
if (!mrb_num_shift(mrb, val, width, &val)) {
int_overflow(mrb, "bit shift");
}
return lshift(mrb, val, width);
return mrb_int_value(mrb, val);
}
/* 15.2.8.3.13 */
@@ -1384,11 +1383,11 @@ int_rshift(mrb_state *mrb, mrb_value x)
}
val = mrb_integer(x);
if (val == 0) return x;
if (width < 0) {
if (width == MRB_INT_MIN) int_overflow(mrb, "bit shift");
return lshift(mrb, val, -width);
if (width == MRB_INT_MIN) int_overflow(mrb, "bit shift");
if (!mrb_num_shift(mrb, val, -width, &val)) {
int_overflow(mrb, "bit shift");
}
return rshift(mrb, val, width);
return mrb_int_value(mrb, val);
}
/* 15.2.8.3.23 */