From 6cba6e5d4fe1d24c0cc00a28219d739281892ec0 Mon Sep 17 00:00:00 2001
From: Guy Perfect <guytpk@gmail.com>
Date: Wed, 30 Oct 2024 10:22:49 -0500
Subject: [PATCH] Prevent disassembling over PC

---
 util/disassembler.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/util/disassembler.c b/util/disassembler.c
index ce0c60f..721499a 100644
--- a/util/disassembler.c
+++ b/util/disassembler.c
@@ -489,8 +489,9 @@ static OpDef* dasmSETF(VBU_DasmConfig *config,
 }
 
 /* Disassemble one instruction */
-static int dasmLine(VB *sim, uint32_t *address, VBU_DasmConfig *config,
-    VBU_DasmLine **lines, size_t *size, size_t *offset, unsigned index) {
+static int dasmLine(VB *sim, uint32_t *address, uint32_t pc,
+    VBU_DasmConfig *config, VBU_DasmLine **lines, size_t *size, size_t *offset,
+    unsigned index) {
     char         *dest;             /* Text output pointer */
     char         *format;           /* Hexadecimal format string */
     VBU_DasmLine *line;             /* Output line */
@@ -501,15 +502,17 @@ static int dasmLine(VB *sim, uint32_t *address, VBU_DasmConfig *config,
     char          tCode[4][3];      /* Code display text */
     char          tMnemonic[8];     /* Mnemonic display text */
     char          tOperands[3][15]; /* Operands display text */
-    unsigned      x;                /* Scratch and iterator */
+    uint32_t      x;                /* Scratch and iterator */
 
     /* Process non-text members */
     line = &(*lines)[index];
     line->address    = *address;
     line->codeLength = dasmInstSize(sim, *address);
-    line->isPC       = vbGetProgramCounter(sim) - *address < line->codeLength;
-    for (x = 0; x < line->codeLength; x++, (*address)++)
-        line->code[x] = vbRead(sim, *address, VB_U8);
+    line->isPC       = *address == pc;
+    for (x = 0; x < line->codeLength; x++)
+        line->code[x] = vbRead(sim, *address + x, VB_U8);
+    *address += pc - *address < line->codeLength ?
+        pc - *address : line->codeLength;
 
     /* Do not process text members */
     if (config == NULL) {
@@ -674,7 +677,7 @@ static VBU_DasmLine* dasmDisassemble(VB *sim, uint32_t address,
 
     /* Process output lines */
     for (x = 0; x < length; x++) {
-        if (dasmLine(sim, &addr, config, &lines, &size, &offset, x))
+        if (dasmLine(sim, &addr, pc, config, &lines, &size, &offset, x))
             goto catch;
     }
     return lines;