From 73f1e24e3c1d38db44d23ceab45b62de33df2428 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Tue, 29 Oct 2019 22:15:44 +0100
Subject: [PATCH] LOAD/SAVE preparation routines should be OK now

---
 STATUS.md                                     |  8 ++---
 .../{f49e.load_int.s => f49e.load_prep.s}     | 13 ++++++++-
 c64/kernal/iostack/f5dd.save_int.s            | 12 --------
 c64/kernal/iostack/f5dd.save_prep.s           | 29 +++++++++++++++++++
 c64/kernal/jumptable/ffd5.jload.s             |  2 +-
 c64/kernal/jumptable/ffd8.jsave.s             |  2 +-
 6 files changed, 47 insertions(+), 19 deletions(-)
 rename c64/kernal/iostack/{f49e.load_int.s => f49e.load_prep.s} (58%)
 delete mode 100644 c64/kernal/iostack/f5dd.save_int.s
 create mode 100644 c64/kernal/iostack/f5dd.save_prep.s

diff --git a/STATUS.md b/STATUS.md
index 448fefa5..d754ca4f 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -128,13 +128,13 @@ NOTE: Even the 'DONE' routines won't support features described as missing in on
 | `$FFC0`   | `$F34A`    | `OPEN`      | DONE     |                                                      |
 | `$FFC3`   | `$F291`    | `CLOSE`     | DONE     |                                                      |
 | `$FFC6`   | `$F20E`    | `CHKIN`     | DONE     |                                                      |
-| `$FFC9`   | `$F250`    | `CKOUT`     | PARTIAL  |                                                      |
+| `$FFC9`   | `$F250`    | `CKOUT`     | DONE     |                                                      |
 | `$FFCC`   | `$F333`    | `CLRCHN`    | DONE     |                                                      |
 | `$FFCF`   | `$F157`    | `CHRIN`     | PARTIAL  |                                                      |
 | `$FFD2`   | `$F1CA`    | `CHROUT`    | PARTIAL  |                                                      |
-| `$FFD5`   | `$F49E`    | `LOAD`      | PARTIAL  | not yet clear what's this entry doing                |
-| `($0330)` | `$F4A5`    | `LOAD`      | PARTIAL  | no VERIFY support, no STOP key, check $F49E addr     |
-| `$FFD8`   | `$F5DD`    | `SAVE`      | NOT DONE |                                                      |
+| `$FFD5`   | `$F49E`    | `LOAD`      | DONE     |                                                      |
+| `($0330)` | `$F4A5`    | `LOAD`      | PARTIAL  | no VERIFY support, no STOP key support               |
+| `$FFD8`   | `$F5DD`    | `SAVE`      | DONE     | only this preparation routine part is done           |
 | `($0332)` | `$F5ED`    | `SAVE`      | NOT DONE |                                                      |
 | `$FFDB`   |            | `SETTIM`    | DONE     |                                                      |
 | `$FFDE`   |            | `RDTIM`     | DONE     |                                                      |
diff --git a/c64/kernal/iostack/f49e.load_int.s b/c64/kernal/iostack/f49e.load_prep.s
similarity index 58%
rename from c64/kernal/iostack/f49e.load_int.s
rename to c64/kernal/iostack/f49e.load_prep.s
index ca8fca9c..cc045026 100644
--- a/c64/kernal/iostack/f49e.load_int.s
+++ b/c64/kernal/iostack/f49e.load_prep.s
@@ -1,11 +1,22 @@
 
+//
+// LOAD preparation routine
+//
+
+//
+// Input (according to http://sta.c64.org/cbm64krnfunc.html)
+// .A        - 0 for load, non-0 for verify
+// .X and .Y - load address (if secondary address is 0)
+//
+
 //
 // Note: Although the vector at $330 points to $F4A5, the Kernal jump table points to $F49E
 // (see also Mapping the C64, page 76). By experimenting I have discovered that $F49E performs
 // indirect jump via ($0330) vector, after setting MEMUSS.
 //
 
-LOAD_INT:
+
+LOAD_PREP:
 
 	sty MEMUSS+1
 	stx MEMUSS+0
diff --git a/c64/kernal/iostack/f5dd.save_int.s b/c64/kernal/iostack/f5dd.save_int.s
deleted file mode 100644
index 7ef54a41..00000000
--- a/c64/kernal/iostack/f5dd.save_int.s
+++ /dev/null
@@ -1,12 +0,0 @@
-
-//
-// XXX Note: something unusual was done with LOAD routine - although the vector at $330 points to $F4A5,
-//           the Kernal jump table points to $F49E (see also Mapping the C64, page 76). By experimenting
-//           I have already discovered that $F4A5 performs indirect jump via ($0330) vector, but it must
-//           be doing a little bit more - not sure yet, what. Something similar is done with SAVE.
-//
-//           This has to be clarified.
-//
-
-SAVE_INT:
-    jmp (ISAVE)
diff --git a/c64/kernal/iostack/f5dd.save_prep.s b/c64/kernal/iostack/f5dd.save_prep.s
new file mode 100644
index 00000000..d7cf3f86
--- /dev/null
+++ b/c64/kernal/iostack/f5dd.save_prep.s
@@ -0,0 +1,29 @@
+
+//
+// SAVE preparation routine
+//
+
+//
+// Input (according to http://sta.c64.org/cbm64krnfunc.html)
+// .A        - address of zero page register holding start address of memory area to save
+// .X and .Y - end address of memory area plus 1
+//
+
+//
+// Note: Experimenting can easily confirm that SAVE preparation routine does similar
+// actions as LOAD preparation routine.
+//
+
+SAVE_PREP:
+
+	sty EAL+1
+	stx EAL+0
+
+	tax
+
+	lda $01, x
+	sta STAL+1
+	lda $00, x
+	sta STAL+0
+
+    jmp (ISAVE)
diff --git a/c64/kernal/jumptable/ffd5.jload.s b/c64/kernal/jumptable/ffd5.jload.s
index ef66f320..002e01fd 100644
--- a/c64/kernal/jumptable/ffd5.jload.s
+++ b/c64/kernal/jumptable/ffd5.jload.s
@@ -1,4 +1,4 @@
 // load RAM from a device
 // C64 Programmer's Reference Guide Page 272
 
-	jmp LOAD_INT
+	jmp LOAD_PREP
diff --git a/c64/kernal/jumptable/ffd8.jsave.s b/c64/kernal/jumptable/ffd8.jsave.s
index 1213f478..25f3fbec 100644
--- a/c64/kernal/jumptable/ffd8.jsave.s
+++ b/c64/kernal/jumptable/ffd8.jsave.s
@@ -1,4 +1,4 @@
 // SAVE RAM to device
 // C64 Programmer's Reference Guide Page 273
 
-	jmp SAVE_INT
+	jmp SAVE_PREP