From 6d74679a5ca7137eb0d433028a7666e77132d00e Mon Sep 17 00:00:00 2001
From: Paul Gardner-Stephen <paul@servalproject.org>
Date: Sat, 4 May 2019 23:52:48 +0930
Subject: [PATCH] set end of loaded memory pointer in BASIC LOAD routine. Other
 small fixes.

---
 c64/basic/cmd_load.s          | 49 +++++++++++++++++++++++++++++++++++
 c64/basic/cmd_unimplemented.s | 19 --------------
 c64/kernal/load.s             | 12 +++++++--
 3 files changed, 59 insertions(+), 21 deletions(-)
 create mode 100644 c64/basic/cmd_load.s

diff --git a/c64/basic/cmd_load.s b/c64/basic/cmd_load.s
new file mode 100644
index 00000000..4090be5b
--- /dev/null
+++ b/c64/basic/cmd_load.s
@@ -0,0 +1,49 @@
+cmd_load:
+
+	;; Parse filename
+	;; (we can tell the KERNAL where it is in memory directly, since the
+	;; KERNAL will be able to peek under ROMs to read it, since it will have
+	;; to be able to peek under the ROMs for SAVE and VERIFY).
+	;; Parse optional device #
+	;; Parse optional secondary address
+	
+	;; XXX - C64 BASIC apparently doesn't clear variables after a LOAD in the
+	;; middle of a program. For safety, we do.
+	jsr basic_do_clr
+	
+	;; Try to load an IEC file
+	lda #0			; use supplied load address, not the one from the file
+	sta current_secondary_address
+	lda #$00 		; LOAD not verify
+	ldx #<$0801		; LOAD address = $0801
+	ldy #>$0801
+	jsr $ffd5
+	bcc +
+
+	;; A = KERNAL error code, which also almost match
+	;; basic ERROR codes, so we can just copy the
+	;; error code to X, decrement, and handle normally
+	tax
+	dex
+	jmp do_basic_error
+	
+*
+	;; $YYXX is the last loaded address, so store it
+	stx basic_end_of_text_ptr+0
+	sty basic_end_of_text_ptr+1
+
+	;; Now relink the loaded program, as we cannot trust the line
+	;; links supplied. For example, the VICE virtual drive emulation
+	;; always supplies $0101 as the address of the next line.
+	
+	;; After LOADing, we either start the program from the beginning,
+	;; or go back to the READY prompt if LOAD was called from direct mode.
+
+	;; Reset to start of program
+	lda basic_start_of_text_ptr+0
+	sta basic_current_line_ptr+0
+	lda basic_start_of_text_ptr+1
+	sta basic_current_line_ptr+1
+
+	;; Try to keep executing
+	jmp basic_execute_statement
diff --git a/c64/basic/cmd_unimplemented.s b/c64/basic/cmd_unimplemented.s
index 4561cd47..56269f91 100644
--- a/c64/basic/cmd_unimplemented.s
+++ b/c64/basic/cmd_unimplemented.s
@@ -20,7 +20,6 @@ cmd_rem:
 cmd_stop:
 cmd_on:
 cmd_wait:
-cmd_load:
 cmd_save:
 cmd_verify:
 cmd_def:
@@ -82,24 +81,6 @@ cmd_go:
 	;; Undefined tokens
 cmd_unimplemented:
 
-	;; Dummy action while testing IEC support
-
-	;; Try to load an IEC file
-	lda #0			; use supplied load address, not the one from the file
-	sta current_secondary_address
-	lda #$00 		; LOAD not verify
-	ldx #<$0801		; LOAD address = $0801
-	ldy #>$0801
-	jsr $ffd5
-	bcc +
-
-	;; A = KERNAL error code, which also almost match
-	;; basic ERROR codes, so we can just copy the
-	;; error code to X, decrement, and handle normally
-	tax
-	dex
-	jmp do_basic_error
 	
-*
 	
 	jmp do_NOT_IMPLEMENTED_error
diff --git a/c64/kernal/load.s b/c64/kernal/load.s
index b53450cb..76a64a60 100644
--- a/c64/kernal/load.s
+++ b/c64/kernal/load.s
@@ -154,13 +154,21 @@ load_done:
 	jsr iec_tx_byte
 	jsr iec_release_atn
 
-	;;  FALL THROUGH
+	;; Return last address written to +1
+	;; (Even though Compute's Mapping the 64 says without the +1.
+	;; I'm suspicious. Will have to check behavour on an original C64)
+	ldx load_save_start_ptr+0
+	ldy load_save_start_ptr+1
+
 	clc
+	cli
+	rts
 	
 load_error:
 
 	;; XXX - Indicate KERNAL (not BASIC) LOAD error condtion
-
+	sec
+	
 	;; Re-enable interrupts and return
 	cli
 	;; (iec_tx_byte will have set/cleared C flag and put result code