From 18d3f30bc4df7070cbd1aa68cce850255a11fb40 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Fri, 1 Jul 2022 13:59:59 -0400
Subject: [PATCH] fs/boot: implement fat16close

---
 fs/fs/boot.fs       | 22 +++++++++++++---------
 fs/tests/fs/boot.fs |  3 ++-
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/fs/fs/boot.fs b/fs/fs/boot.fs
index 9c0adf0e..738f2ac8 100644
--- a/fs/fs/boot.fs
+++ b/fs/fs/boot.fs
@@ -86,7 +86,7 @@ create fnbuf FNAMESZ allot
   2drop ;
 
 \ File cursor
-\ 2b first cluster
+\ 2b first cluster 0=free cursor
 \ 2b current cluster in buf
 \ 4b cur pos (offset from beginning of file)
 \ 4b file size
@@ -102,18 +102,20 @@ create fnbuf FNAMESZ allot
 : FCUR_size ( fcur -- n ) 8 + @ ;
 : FCUR_buf( ( fcur -- a ) 12 + ;
 
-create fcursors( FCursorSize FCURSORCNT * allot
-here value )fcursor
-fcursors( value nextfcursor
+create fcursors( FCursorSize FCURSORCNT * allot0
+
+: findfreecursor ( -- fcursor )
+  FCURSORCNT >r fcursors( begin ( a )
+    dup FCUR_cluster0 not if ( found! ) r~ exit then FCursorSize + next
+  abort" out of file cursors!" ;
 
 \ Open the specified "direntry" into one of the free cursors and return that
 \ cursor.
 : openfile ( direntry -- fcursor )
-  nextfcursor )fcursor = if abort" out of file cursors!" then
-  dup DIR_Cluster ( dirent cluster ) dup nextfcursor FCUR_buf( readcluster
-  ( dirent cluster ) dup nextfcursor w! nextfcursor FCUR_cluster! ( dirent )
-  0 nextfcursor 4 + ! DIR_FileSize nextfcursor 8 + ! ( )
-  nextfcursor FCursorSize to+ nextfcursor ( fcursor ) ;
+  findfreecursor >r
+  dup DIR_Cluster ( dirent cluster ) dup r@ FCUR_buf( readcluster
+  ( dirent cluster ) dup r@ w! r@ FCUR_cluster! ( dirent )
+  0 r@ 4 + ! DIR_FileSize r@ 8 + ! ( ) r> ;
 
 : fat16getc ( fcursor -- c-or-0 )
   dup FCUR_pos over FCUR_size = if drop 0 exit then
@@ -125,3 +127,5 @@ fcursors( value nextfcursor
       rot 2dup FCUR_cluster! ( c cluster fc )
       tuck FCUR_buf( readcluster ( c fc ) swap then
   then ( fc c ) nip ;
+
+: fat16close ( fcursor ) 0 swap w! ;
diff --git a/fs/tests/fs/boot.fs b/fs/tests/fs/boot.fs
index ade09af0..a8d8fb9f 100644
--- a/fs/tests/fs/boot.fs
+++ b/fs/tests/fs/boot.fs
@@ -19,5 +19,6 @@ dup $fd readN ( fcursor )
 dup fat16getc 'b' #eq
 dup $dfc readN ( fcursor )
 dup fat16getc 'E' #eq dup fat16getc 'O' #eq dup fat16getc 'F' #eq
-fat16getc 0 #eq
+dup fat16getc 0 #eq
+fat16close
 testend
-- 
2.45.2