From 68b61f4c8cea540d89537be56c05f1a9edc03536 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Sun, 6 Oct 2019 17:06:42 +0200
Subject: [PATCH] provided LINKPRG routine

---
 STATUS.md                |  2 +-
 c64/basic/a533.linkprg.s | 91 ++++++++++++++++++++++++++++++++++++++--
 c64/basic/cmd_load.s     | 86 +------------------------------------
 c64/kernal/f4a5.load.s   |  2 +-
 4 files changed, 91 insertions(+), 90 deletions(-)

diff --git a/STATUS.md b/STATUS.md
index dd27dfb2..65edf246 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -76,7 +76,7 @@ Not all of them - only these we want to have implemented.
 | Address   | Name         | Status   |  Remarks                                           |
 | :-------: | :----------- | :------: | :------------------------------------------------: |
 | `$A004`   | revision str | DONE     |                                                    |
-| `$A533`   | LINKPRG      | NOT DONE |                                                    |
+| `$A533`   | LINKPRG      | DONE     |                                                    |
 | `$A659`   | set txt ptr  | NOT DONE |                                                    |
 | `$A68E`   | RUNC         | NOT DONE |                                                    |
 | `$A7AE`   | NEWSTT       | NOT DONE |                                                    |
diff --git a/c64/basic/a533.linkprg.s b/c64/basic/a533.linkprg.s
index b7b11e80..675a794e 100644
--- a/c64/basic/a533.linkprg.s
+++ b/c64/basic/a533.linkprg.s
@@ -1,6 +1,91 @@
 
-// XXX provide documentation and implementation
-// see: https://www.lemon64.com/forum/viewtopic.php?t=64721&sid=bc400a5a6d404f8f092e4d32a92f5de7
+//
+// Well-known BASIC routine, described in:
+//
+// - [CM64] Compute's Mapping the Commodore 64 - page 95
+// - https://www.lemon64.com/forum/viewtopic.php?t=64721&sid=bc400a5a6d404f8f092e4d32a92f5de7
+//
 
 LINKPRG:
-    STUB_IMPLEMENTATION()
+
+	// Start by getting pointer to the first line
+	jsr init_oldtxt
+
+linkprg_loop:
+	// Is the pointer to the end of the program
+	ldy #1
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<OLDTXT+0
+	jsr peek_under_roms
+	cmp #$00
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (OLDTXT),y
+#endif
+
+	bne !+
+
+	// End of program
+	rts
+!:
+	// Now search forward to find the end of the line
+	// Skip forward pointer and line number
+	ldy #4
+
+linkprg_end_of_line_search:
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<OLDTXT+0
+	jsr peek_under_roms
+#else // CONFIG_MEMORY_MODEL_38K
+	lda (OLDTXT),y
+#endif
+
+	cmp #$00
+	beq !+
+
+	// Not yet end of line
+	iny
+	bne linkprg_end_of_line_search
+
+	// line too long
+	jmp do_STRING_TOO_LONG_error
+
+!:
+	// Found end of line, so update pointer
+
+	// First, skip over the $00 char
+	iny
+
+	// Now overwrite the pointer (carefully)
+	//
+	tya
+	clc
+	adc OLDTXT+0
+	pha
+	php
+	ldy #0
+
+#if CONFIG_MEMORY_MODEL_60K
+	ldx #<OLDTXT+0
+	jsr poke_under_roms
+#else // CONFIG_MEMORY_MODEL_38K
+	sta (OLDTXT),y
+#endif
+
+	plp
+	lda OLDTXT+1
+	adc #0
+	ldy #1
+
+#if CONFIG_MEMORY_MODEL_60K
+	jsr poke_under_roms
+#else // CONFIG_MEMORY_MODEL_38K
+	sta (OLDTXT),y
+#endif
+
+	sta OLDTXT+1
+	pla
+	sta OLDTXT+0
+
+	jmp linkprg_loop
diff --git a/c64/basic/cmd_load.s b/c64/basic/cmd_load.s
index d54960a4..6fa4adc6 100644
--- a/c64/basic/cmd_load.s
+++ b/c64/basic/cmd_load.s
@@ -112,7 +112,7 @@ got_loadaddress:
 	// 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.
-	jsr basic_relink_program
+	jsr LINKPRG
 	
 	// After LOADing, we either start the program from the beginning,
 	// or go back to the READY prompt if LOAD was called from direct mode.
@@ -122,87 +122,3 @@ got_loadaddress:
 
 	// XXX - should run program if LOAD was used in program mode
 	jmp basic_main_loop
-
-
-basic_relink_program:
-
-	// Start by getting pointer to the first line
-	jsr init_oldtxt
-
-basic_relink_loop:
-	// Is the pointer to the end of the program
-	ldy #1
-
-#if CONFIG_MEMORY_MODEL_60K
-	ldx #<OLDTXT+0
-	jsr peek_under_roms
-	cmp #$00
-#else // CONFIG_MEMORY_MODEL_38K
-	lda (OLDTXT),y
-#endif
-
-	bne !+
-
-	// End of program
-	rts
-!:
-	// Now search forward to find the end of the line
-	// Skip forward pointer and line number
-	ldy #4
-end_of_line_search:
-
-#if CONFIG_MEMORY_MODEL_60K
-	ldx #<OLDTXT+0
-	jsr peek_under_roms
-#else // CONFIG_MEMORY_MODEL_38K
-	lda (OLDTXT),y
-#endif
-
-	cmp #$00
-	beq !+
-
-	// Not yet end of line
-	iny
-	bne end_of_line_search
-
-	// line too long
-	jmp do_STRING_TOO_LONG_error
-
-!:
-	// Found end of line, so update pointer
-
-	// First, skip over the $00 char
-	iny
-
-	// Now overwrite the pointer (carefully)
-	//
-	tya
-	clc
-	adc OLDTXT+0
-	pha
-	php
-	ldy #0
-
-#if CONFIG_MEMORY_MODEL_60K
-	ldx #<OLDTXT+0
-	jsr poke_under_roms
-#else // CONFIG_MEMORY_MODEL_38K
-	sta (OLDTXT),y
-#endif
-
-	plp
-	lda OLDTXT+1
-	adc #0
-	ldy #1
-
-#if CONFIG_MEMORY_MODEL_60K
-	jsr poke_under_roms
-#else // CONFIG_MEMORY_MODEL_38K
-	sta (OLDTXT),y
-#endif
-
-	sta OLDTXT+1
-	pla
-	sta OLDTXT+0
-
-	jmp basic_relink_loop
diff --git a/c64/kernal/f4a5.load.s b/c64/kernal/f4a5.load.s
index 0a838d91..e1cccc1d 100644
--- a/c64/kernal/f4a5.load.s
+++ b/c64/kernal/f4a5.load.s
@@ -142,6 +142,6 @@ load_loop:
 
 	lda FA
 	jsr close_load
-.break
+
 	// Return last address
 	jmp lvs_return_last_address