From 5d7e943a7924c17618c19ce0a13f07c88f3a4456 Mon Sep 17 00:00:00 2001
From: Toni Wilen <twilen@winuae.net>
Date: Fri, 1 Oct 2021 22:50:27 +0300
Subject: [PATCH] Another 68000 IPL poll timing update.

---
 gencpu.cpp | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/gencpu.cpp b/gencpu.cpp
index df66b895..cd328b76 100644
--- a/gencpu.cpp
+++ b/gencpu.cpp
@@ -158,6 +158,7 @@ static int brace_level;
 
 static char outbuffer[30000];
 static int last_access_offset_ipl;
+static int last_access_offset_ipl_prev;
 
 static void out(const char *format, ...)
 {
@@ -245,6 +246,12 @@ static void set_last_access_ipl(void)
 	last_access_offset_ipl = strlen(outbuffer);
 }
 
+static void set_last_access_ipl_prev(void)
+{
+	last_access_offset_ipl_prev = strlen(outbuffer);
+}
+
+
 NORETURN static void term (void)
 {
 	out("Abort!\n");
@@ -486,7 +493,17 @@ static bool isprefetch020(void)
 
 static void check_ipl(void)
 {
-	set_last_access_ipl();
+	// So far it seems 68000 IPL fetch happens when CPU is doing
+	// memory cycle data part followed by prefetch cycle. It must
+	// happen after possible bus error has been detected but before
+	// following prefetch memory cycle.
+	if (last_access_offset_ipl_prev < 0) {
+		set_last_access_ipl();
+	} else {
+		// if memory cycle happened previously: use it.
+		last_access_offset_ipl = last_access_offset_ipl_prev;
+		ipl_fetched = 1;
+	}
 }
 
 static void check_ipl_always(void)
@@ -3636,6 +3653,8 @@ static void genamode2x (amodes mode, const char *reg, wordsizes size, const char
 		addmmufixup(reg, size, mode);
 	}
 
+	set_last_access_ipl_prev();
+
 	if (getv == 1) {
 		const char *srcbx = !(flags & GF_FC) ? srcb : "sfc_nommu_get_byte";
 		const char *srcwx = !(flags & GF_FC) ? srcw : "sfc_nommu_get_word";
@@ -3881,6 +3900,8 @@ static void genastore_2 (const char *from, amodes mode, const char *reg, wordsiz
 		check_address_error(to, mode, reg, size, 2, 0, flags);
 	}
 
+	set_last_access_ipl_prev();
+
 	switch (mode) {
 	case Dreg:
 		switch (size) {
@@ -4007,6 +4028,7 @@ static void genastore_2 (const char *from, amodes mode, const char *reg, wordsiz
 						fill_prefetch_next_after(0, NULL);
 						insn_n_cycles += 4;
 					}
+					set_last_access_ipl_prev();
 					out("%s(%sa, %s >> 16);\n", dstwx, to, from);
 					sprintf(tmp, "%s >> 16", from);
 					count_writew++;
@@ -4019,6 +4041,7 @@ static void genastore_2 (const char *from, amodes mode, const char *reg, wordsiz
 					if (flags & GF_SECONDWORDSETFLAGS) {
 						genflags(flag_logical, g_instr->size, "src", "", "");
 					}
+					set_last_access_ipl_prev();
 					out("%s(%sa + 2, %s);\n", dstwx, to, from);
 					count_writew++;
 					check_bus_error(to, 2, 1, 1, from, 1, pcoffset);
@@ -4055,6 +4078,7 @@ static void genastore_2 (const char *from, amodes mode, const char *reg, wordsiz
 					if (store_dir > 1) {
 						fill_prefetch_next_after(0, NULL);
 					}
+					set_last_access_ipl_prev();
 					out("%s(%sa, %s >> 16); \n", dstwx, to, from);
 					sprintf(tmp, "%s >> 16", from);
 					count_writew++;
@@ -4067,6 +4091,7 @@ static void genastore_2 (const char *from, amodes mode, const char *reg, wordsiz
 					if (flags & GF_SECONDWORDSETFLAGS) {
 						genflags(flag_logical, g_instr->size, "src", "", "");
 					}
+					set_last_access_ipl_prev();
 					out("%s(%sa + 2, %s); \n", dstwx, to, from);
 					count_writew++;
 					check_bus_error(to, 2, 1, 1, from, 1, pcoffset);
@@ -5267,6 +5292,7 @@ static void gen_opcode (unsigned int opcode)
 	bus_error_code2[0] = 0;
 	opcode_nextcopy = 0;
 	last_access_offset_ipl = -1;
+	last_access_offset_ipl_prev = -1;
 
 	loopmode = 0;
 	// 68010 loop mode available if
-- 
2.47.3