old_logic_table.md

Internal Logic

RoundNearest

sign of hi	sign of lo	rounding	fastrounding
+	+	hi	hi
+	-	hi	hi
-	+	hi	hi
-	-	hi	hi

RoundDown

sign of hi	sign of lo	rounding	fastrounding
+	+	hi	hi
+	-	prevfloat(hi)	next_nearerto_zero(hi) == prev_float(hi)
-	+	hi	hi
-	-	prevfloat(hi)	next_awayfrom_zero(hi) == prev_float(hi)

RoundUp

sign of hi	sign of lo	rounding	fastrounding
+	+	nextfloat(hi)	next_awayfrom_zero(hi) == next_float(hi)
+	-	hi	hi
-	+	nextfloat(hi)	next_nearerto_zero(hi) == next_float(hi)
-	-	hi	hi

RoundFromZero

sign of hi	sign of lo	rounding	fastrounding
+	+	nextfloat(hi)	next_awayfrom_zero(hi)
+	-	hi	hi
-	+	hi	hi
-	-	prevfloat(hi)	next_awayfrom_zero(hi)

RoundToZero

sign of hi	sign of lo	rounding	fastrounding
+	+	hi	hi
+	-	prevfloat(hi)	next_nearerto_zero(hi)
-	+	nextfloat(hi)	next_nearerto_zero(hi)
-	-	hi	hi