duskos

commit 5cc5dd2753a35430439dade6fbdcac1fa94ebee7
parent a5349884cd7abd3e89b22dfacc4e43e068ea68c4
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Thu,  1 Sep 2022 16:04:14 -0400

Add "rfree"

See doc/usage

Diffstat:
M
fs/doc/usage.txt
 | 
12
+++++++++++-
M
fs/fs/fatlo.fs
 | 
2
+-
M
fs/tests/kernel.fs
 | 
2
+-
M
fs/xcomp/bootlo.fs
 | 
2
++
M
fs/xcomp/pc/build.fs
 | 
2
+-

5 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/fs/doc/usage.txt b/fs/doc/usage.txt
@@ -106,7 +106,7 @@ V1=RSTART-4 and V4=RSTART-16.
 When using local variables, you are responsible with pushing and popping to/from
 RS. All those variables give you are "to" semantics to a "RS slot". Example:
 
-: foo ( a b c -- ) >r >r >r V1 . spc> V2 . spc> V3 . rdrop rdrop rdrop ;
+: foo ( a b c -- ) >r >r >r V1 . spc> V2 . spc> V3 . rfree ;
 
 1 2 3 foo \ prints "3 2 1"
 
@@ -117,6 +117,16 @@ RS. All those variables give you are "to" semantics to a "RS slot". Example:
 : inc5 ( a -- a+5 ) >r 5 >r begin 1 to+ V1 next V1 rdrop ;
 42 inc5 . \ prints 47
 
+## rfree
+
+What's this "rfree" used above? It's an automatic RS adjuster. It looks at the
+"R counter" and emits an RS adjustment equivalent to its current level, and then
+sets this level to 0. In the example above, it's equivalent to "rdrop rdrop
+rdrop".
+
+Be aware that the "R counter" is not always accurate! If you have conditional
+modifications to RS levels, "rfree" is going to be broken. See section below.
+
 ## Manual [rcnt] adjustments
 
 The "R counter" that determines local variable slots is oblivious to conditional
diff --git a/fs/fs/fatlo.fs b/fs/fs/fatlo.fs
@@ -256,7 +256,7 @@ extends _FAT struct[ FATLO
       DirEntry SZ + dup V1 _FAT :)buf = if
        drop V1 _FAT :nextsector? not if
         rootdirentry( ( parses as "lastentry" ) else V1 _FAT :buf( then then
-    repeat ( a ) drop rdrop rdrop ;
+    repeat ( a ) drop rfree ;
 
   : :child ( dirid name self -- id-or-0 ) >r
     fnbuf! r@ _FAT :getdirentry r@ _FAT :readdir r@ _FAT :findindir
diff --git a/fs/tests/kernel.fs b/fs/tests/kernel.fs
@@ -83,7 +83,7 @@ ll llcnt 3 #eq
 42 ' bar emeta findemeta ( ll ) #eq
 
 \ Local variables
-: foo 54 >r 42 >r 1 to+ V1 2 to+ V2 V2 V1 rdrop rdrop ;
+: foo 54 >r 42 >r 1 to+ V1 2 to+ V2 V2 V1 rfree ;
 foo 55 #eq 44 #eq
 : inc5 >r 5 >r begin 1 to+ V1 next V1 rdrop ;
 42 inc5 47 #eq
diff --git a/fs/xcomp/bootlo.fs b/fs/xcomp/bootlo.fs
@@ -62,6 +62,8 @@ code : ] code ] ;
 : ^ -1 xor ;
 : upcase ( c -- c ) dup 'a' - 26 < if $df and then ;
 
+: rfree 0 [rcnt] @! neg r+, ; immediate
+
 \ Local variables + beginning of compiling words
 : create code compile (cell) ;
 : const code litn exit, ;
diff --git a/fs/xcomp/pc/build.fs b/fs/xcomp/pc/build.fs
@@ -41,7 +41,7 @@ create _buf SECSZ allot0
   V2 bootfs 0 Path :new Path :find# Path :copyfile
   V3 bootfs 0 Path :new Path :find#
   S" /init.fs" V1 0 Path :new Path :find# Path :appendfile
-  rdrop rdrop rdrop ;
+  rfree ;
 
 : buildPC ( drv clustercnt -- fat ) over >r \ V1=drv
   ." creating FAT and copying files" nl>