From e3358fd1d3f12f7af6eadb39e668889c5a7e7565 Mon Sep 17 00:00:00 2001
From: d6 <d_m@plastic-idolatry.com>
Date: Sat, 9 Apr 2022 00:05:12 -0400
Subject: [PATCH] open empty files, error on large files

---
 femto.tal | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/femto.tal b/femto.tal
index 52e41bd..f995dc6 100644
--- a/femto.tal
+++ b/femto.tal
@@ -35,7 +35,7 @@
 |10 @Console    [ &vector $2 &read $1 &pad    $5 &write $1 &error  $1 ]
 |a0 @File       [ &vector $2 &success $2 &stat $2 &delete $1 &append $1 &name $2 &length $2 &read $2 &write $2 ]
 
-( MAX file size is currently #d200, i.e. 532926 bytes )
+( MAX file size is currently #d200, i.e. 53760 bytes )
 
 %dbg { #ff .System/debug DEO }
 %emit { .Console/write DEO }
@@ -190,10 +190,11 @@
 ( TODO: enable closing/opening files with editor already running )
 @open-file ( filename* -> )
                  .File/name   DEO2
-           #d200 .File/length DEO2
+           #d201 .File/length DEO2
     ;data .File/read   DEO2
 
-    .File/success DEI2 #0000 GTH2 ,&ok JCN
+    .File/success DEI2 #0000 EQU2 .state/modified STZ
+    .File/success DEI2 #d201 LTH2 ,&ok JCN
     ;messages/input-error ;print JSR2
     ;filename ;print JSR2 nl quit!
 
@@ -1195,9 +1196,6 @@
     LIT 's .config/insert-tabs LDZ ADD emit
     emit-] sp emit-u emit-:
     ;undo-stack/pos LDA2 ;undo-stack/data SUB2 #0003 DIV2 ;emit-dec2 JSR2
-(    sp
-    ;undo-stack/pos LDA2 #0003 SUB2 LDA2k ;emit-dec2 JSR2 sp
-    INC2 INC2 LDA #00 SWP ;emit-dec2 JSR2 ( ) )
 
    ;emit-reset JMP2
 
@@ -1553,7 +1551,7 @@
 
 ( various string constants used as messages for the user )
 @messages [ &null 00
-            &input-error "Input 20 "error: 20 00
+            &input-error "Input 20 "error, 20 "file 20 "too 20 "large: 20 00
             &bytes 20 "bytes, 00
             &save-ok "Successfully 20 "saved 20 00
             &save-failed "Failed 20 "to 20 "save 20 00
@@ -1608,6 +1606,16 @@
 ( path to file being edited )
 @filename $80
 
+( stack of data to undo )
+( )
+( each item in the stack consists of: )
+(  - 2 bytes: address to jump to )
+(  - 1 byte: character to insert, or \0 to delete )
+( )
+( pos points to the next open stack frame. )
+( )
+( when pos points to data the stack is empty, and )
+( when pos points to pos the stack is full. )
 @undo-stack [
     &data $180 ( 128 steps )
     &pos :undo-stack/data