From f0859c8356c1f99590bfea7746cb267c6c54e12e Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Mon, 2 Dec 2024 20:16:39 -0500
Subject: [PATCH] the assembler allows relative instructions (per, bra, etc) to
 external labels which won't link correctly.  Merlin flags them as an error.

Additionally, per was generating a relocation record which causes the linked code to be wrong (even with an internal label).
---
 src/asm/asm.eval.s    | 41 +++++++++++++++++++++++++++++++++++++++++
 src/asm/asm.opcodes.s | 23 ++++++-----------------
 2 files changed, 47 insertions(+), 17 deletions(-)

diff --git a/src/asm/asm.eval.s b/src/asm/asm.eval.s
index 366024d..cf25664 100644
--- a/src/asm/asm.eval.s
+++ b/src/asm/asm.eval.s
@@ -1439,3 +1439,44 @@ cnvttbl       adrl  0,1,2,3,4,5,6,7,8,9
               adrl  0,1000000000,2000000000,3000000000,4000000000,5000000000
               adrl  6000000000,7000000000,8000000000,900000000
 
+
+
+eval_rel
+* like eval but returns an error if this is a reference to an external label
+* assumes 16-bit m/x
+
+* lableused values:
+* $ffff - no labels encountered in eval (eg, $1234)
+* $7fff - relative value (eg, *)
+* 0-$7ffe - label # ; may be internal or external.
+
+              mx    %00
+              jsr   eval
+              bcc   :check
+              rts
+
+:check        lda   lableused
+              bmi   :ok                  ; merlin allows it...
+              cmp   #$7fff
+              beq   :ok
+              asl
+              asl
+              tay
+              lda   [lableptr1],y
+              sta   lableptr
+              iny
+              iny
+              lda   [lableptr1],y
+              sta   lableptr+2
+              ldy   #o_labtype
+              lda   [lableptr],y
+              bit   #externalbit
+              beq   :ok
+
+              sec
+              lda #badrelative           ; merlin: bad external (bra, etc) 
+              rts                        ; or or illegal forward ref (brl/per)
+
+:ok           clc
+              rts
+
diff --git a/src/asm/asm.opcodes.s b/src/asm/asm.opcodes.s
index 86a8828..e457c5d 100644
--- a/src/asm/asm.opcodes.s
+++ b/src/asm/asm.opcodes.s
@@ -7,7 +7,7 @@ dobranch
               ldy       passnum
               jeq       :p1
               ldx       #$00
-              jsr       eval
+              jsr       eval_rel
               bcc       :offset
               jmp       :errput2
 :offset       lda       objptr
@@ -73,7 +73,7 @@ dobranch
               ldy       passnum
               beq       :p1
               ldx       #$00
-              jsr       eval
+              jsr       eval_rel
               bcc       :offset1
               jmp       :errput3
 :offset1      lda       objptr
@@ -446,16 +446,10 @@ perop         lda       passnum
               and       #amforce24.amforce16.amforce8!$FFFF
               bne       :bad
               ldx       #$00
-              jsr       eval
+              jsr       eval_rel
               bcc       :ok
               rts
-:ok           lda       #relflag                                              ;if rel'ing you can't use an
-              bit       modeflag                                              ;absolute value
-              beq       :ok1
-              bit       lableused
-              bpl       :ok1
-                                                                              ;check for lableused
-:ok1          lda       objptr
+:ok           lda       objptr
               clc
               adc       #$03
               pha
@@ -470,13 +464,8 @@ perop         lda       passnum
               jsr       putbyte
               lda       lvalue+1
               jsr       putbyte
-              lda       #$7fff
-              sta       lableused
-              lda       lvalue
-              sta       noshift
-              jmp       relcorrect
-* clc
-* rts
+              clc
+              rts
 :bad          lda       #badaddress
               sec
               rts