shithub: mc

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Fix dates in the BC

--- a/lib/date/date.myr

+++ b/lib/date/date.myr

@@ -26,6 +26,7 @@

 const Days400y	= 365*400 + 4*25 - 3

 const Days4y	= 365*4 + 1

 const DayUsec	= (24*60*60*1_000_000)

+const Mdays	= [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

 const utcnow = {

 	-> mkinstant(std.now(), "")

@@ -70,10 +71,13 @@

 	inst.us  = (t % 1_000_000) castto(int)

 	t /= 1_000_000

 	inst.s = (t % 60) castto(int)

+	std.assert(inst.s >= 0, "inst.s negative??\n")

 	t /= 60

 	inst.m = (t % 60) castto(int)

+	std.assert(inst.m >= 0, "inst.m negative??\n")

 	t /= 60

 	inst.h = t castto(int)

+	std.assert(inst.h >= 0, "inst.h negative??\n")

 	/* weekday */

 	inst.wday = ((e + 4) % 7) castto(int)	/* the world started on Thursday */

@@ -88,9 +92,7 @@

 	Lots of magic. Yer a wizard, 'arry.

 	*/

 	j = (tm + 2440588 * DayUsec) / DayUsec 

-	std.put("j = {}\n", j)

 	j -= 1721119

-	std.assert(j > 0, "date too negative")

 	y = (4 * j - 1) / Days400y

 	j = 4 * j - 1 - Days400y * y

@@ -115,6 +117,13 @@

 	/* there's no year 0 */

 	if y <= 0

 		y--

+	;;

+	/* and if j negative, the day and month are also negative */

+	if m < 0

+		m += 12

+	;;

+	if d < 0

+		d += Mdays[m - 1] 

 	;;

 	inst.year = y castto(int)

--- a/lib/date/fmt.myr

+++ b/lib/date/fmt.myr

@@ -22,6 +22,7 @@

 const Timefmt	= "%h:%m:{} %z"

 const Datefmt	= "%Y-%m-%d %z"

+/* Always formats in proleptic Gregorian format */

 const sbfmt = {sb, ap, opts

 	var d : instant

 	var fmt

--- a/lib/date/test/fmt.myr

+++ b/lib/date/test/fmt.myr

@@ -28,6 +28,10 @@

 	/* large negative time stamp */

 	d = date.mkinstant(-50000000000*1_000_000, "")

 	eq("385-7-25 07:06:40 +0000", std.bfmt(buf[:], "{D}", d))

+

+	/* date in the bc */

+	d = date.mkinstant(-70000000000*1_000_000, "")

+	eq("-249-11-19 19:33:20 +0000", std.bfmt(buf[:], "{D}", d))

 }

 const eq = {expected, actual