From 0dc9d15cdcc9cadffaeec9dfbc2b047fe064fee4 Mon Sep 17 00:00:00 2001
From: Oxore <oxore@protonmail.com>
Date: Sun, 25 Sep 2022 18:05:16 +0300
Subject: Add Z80 BUSREQ and sound RAM

---
 bus.cpp | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

(limited to 'bus.cpp')

diff --git a/bus.cpp b/bus.cpp
index 9697c09..f611eba 100644
--- a/bus.cpp
+++ b/bus.cpp
@@ -12,8 +12,13 @@
 #include <cstdint>
 #include <cstdlib>
 
+namespace Adr {
+static constexpr uint32_t kZ80BusReq = 0x00a11100;
+}
+
 unsigned char g_rom[ROM_SIZE] = {};
 unsigned char g_ram[RAM_SIZE] = {};
+unsigned char g_sound_ram[SOUND_RAM_SIZE] = {};
 unsigned char g_io1[IO1_SIZE] = {};
 unsigned char g_io2[IO2_SIZE] = {};
 
@@ -25,6 +30,13 @@ static void exit_error(const char* fmt, ...)
     va_start(args, fmt);
     vfprintf(stderr, fmt, args);
     va_end(args);
+    static bool in_error = false;
+    if (in_error)
+    {
+        fprintf(stderr, "Nested error\n");
+        return;
+    }
+    in_error = true;
     fprintf(stderr, "\n");
     unsigned int pc = m68k_get_reg(NULL, M68K_REG_PPC);
     char buff[100];
@@ -82,6 +94,11 @@ static inline struct read_result memory_read(
             memory_read_concrete(bitness, g_ram, address - RAM_START),
             true,
         };
+    } else if (is_in_range(address, SOUND_RAM_START, SOUND_RAM_SIZE)) {
+        return read_result{
+            memory_read_concrete(bitness, g_sound_ram, address - SOUND_RAM_START),
+            true,
+        };
     } else if (is_in_range(address, IO1_START, IO1_SIZE)) {
         return read_result{
             memory_read_concrete(bitness, g_io1, address - IO1_START),
@@ -130,8 +147,18 @@ static inline bool memory_write(
     } else if (is_in_range(address, RAM_START, RAM_SIZE)) {
         memory_write_concrete(bitness, g_ram, address - RAM_START, value);
         return true;
+    } else if (is_in_range(address, SOUND_RAM_START, SOUND_RAM_SIZE)) {
+        memory_write_concrete(bitness, g_sound_ram, address - SOUND_RAM_START, value);
+        return true;
     } else if (is_in_range(address, IO1_START, IO1_SIZE)) {
         memory_write_concrete(bitness, g_io1, address - IO1_START, value);
+        if (address == Adr::kZ80BusReq || address == Adr::kZ80BusReq + 1) {
+            if (g_io1[Adr::kZ80BusReq - IO1_START] == 1 && g_io1[Adr::kZ80BusReq - IO1_START + 1] == 0) {
+                // Acknowledge S80 BUSREQ
+                g_io1[Adr::kZ80BusReq - IO1_START + 0] = 0;
+                g_io1[Adr::kZ80BusReq - IO1_START + 1] = 0;
+            }
+        }
         return true;
     } else if (is_in_range(address, IO2_START, IO2_SIZE)) {
         memory_write_concrete(bitness, g_io2, address - IO2_START, value);
@@ -199,7 +226,7 @@ void m68k_write_memory_8(unsigned int address, unsigned int value)
     m68k_write_callback(address, 1);
     const bool successful = memory_write(BITNESS_8, address, value);
     if (!successful)
-        exit_error("Attempted to write %02x (u8) to address %08x", value&0xff, address);
+        exit_error("Attempted to write 0x%02x (u8) to address %08x", value&0xff, address);
 }
 
 void m68k_write_memory_16(unsigned int address, unsigned int value)
@@ -208,7 +235,7 @@ void m68k_write_memory_16(unsigned int address, unsigned int value)
     m68k_write_callback(address, 2);
     const bool successful = memory_write(BITNESS_16, address, value);
     if (!successful)
-        exit_error("Attempted to write %04x (u16) to address %08x", value&0xffff, address);
+        exit_error("Attempted to write 0x%04x (u16) to address %08x", value&0xffff, address);
 }
 
 void m68k_write_memory_32(unsigned int address, unsigned int value)
@@ -217,5 +244,5 @@ void m68k_write_memory_32(unsigned int address, unsigned int value)
     m68k_write_callback(address, 4);
     const bool successful = memory_write(BITNESS_16, address, value);
     if (!successful)
-        exit_error("Attempted to write %08x (u32) to address %08x", value, address);
+        exit_error("Attempted to write 0x%08x (u32) to address %08x", value, address);
 }
-- 
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