From 221e8e942334bd1fedff21754984cb7a411b1946 Mon Sep 17 00:00:00 2001
From: Chris Hanson <org/chris-hanson/cph>
Date: Thu, 26 Jan 2017 14:57:37 -0800
Subject: [PATCH] Implement fix:end-index and fix:start-index.

---
 src/runtime/fixart.scm  | 18 ++++++++++++++++++
 src/runtime/runtime.pkg |  2 ++
 2 files changed, 20 insertions(+)

diff --git a/src/runtime/fixart.scm b/src/runtime/fixart.scm
index fecafb7a9..9d88f5a10 100644
--- a/src/runtime/fixart.scm
+++ b/src/runtime/fixart.scm
@@ -142,6 +142,24 @@ USA.
 		(fix:- value step)
 		(cons value result))
 	  result))))
+
+(define (fix:end-index end length #!optional caller)
+  (if (default-object? end)
+      length
+      (begin
+	(guarantee index-fixnum? end caller)
+	(if (not (fix:<= end length))
+	    (error:bad-range-argument end caller))
+	end)))
+
+(define (fix:start-index start end #!optional caller)
+  (if (default-object? start)
+      0
+      (begin
+	(guarantee index-fixnum? start caller)
+	(if (not (fix:<= start end))
+	    (error:bad-range-argument start caller))
+	start)))
 
 ;;;; Flonums
 
diff --git a/src/runtime/runtime.pkg b/src/runtime/runtime.pkg
index 6d4dd39bc..1d6a1f68e 100644
--- a/src/runtime/runtime.pkg
+++ b/src/runtime/runtime.pkg
@@ -211,6 +211,7 @@ USA.
 	  fix:and
 	  fix:andc
 	  fix:divide
+	  fix:end-index
 	  fix:fixnum?
 	  fix:gcd
 	  fix:iota
@@ -225,6 +226,7 @@ USA.
 	  fix:quotient
 	  fix:remainder
 	  fix:smallest-value
+	  fix:start-index
 	  fix:xor
 	  fix:zero?
 	  fixnum?
-- 
2.25.1