From 92f7a430ca1c8598514ce5800d28a287d01f699c Mon Sep 17 00:00:00 2001
From: kub <derkub@gmail.com>
Date: Mon, 3 Jan 2022 23:36:44 +0100
Subject: [PATCH] libretro, improve 32x save/load for run-ahead

---
 pico/state.c                 | 3 +++
 platform/libretro/libretro.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/pico/state.c b/pico/state.c
index 307e5d65..f1a67fee 100644
--- a/pico/state.c
+++ b/pico/state.c
@@ -347,6 +347,7 @@ static int state_save(void *file)
       CHECKED_WRITE(chwc->chunk, chwc->size, chwc->ptr);
   }
 
+  CHECKED_WRITE(0, 0, NULL);
   retval = 0;
 
 out:
@@ -540,6 +541,8 @@ static int state_load(void *file)
         break;
 #endif
       default:
+        if (len|chunk == 0)
+           goto readend;
         if (carthw_chunks != NULL)
         {
           carthw_state_chunk *chwc;
diff --git a/platform/libretro/libretro.c b/platform/libretro/libretro.c
index 0af186b0..8aadedf7 100644
--- a/platform/libretro/libretro.c
+++ b/platform/libretro/libretro.c
@@ -872,9 +872,14 @@ int state_fseek(void *file, long offset, int whence)
 size_t retro_serialize_size(void)
 {
    struct savestate_state state = { 0, };
+   unsigned AHW = PicoIn.AHW;
    int ret;
 
+   /* we need the max possible size here, so include 32X for MD and MCD */
+   if (!(AHW & (PAHW_SMS|PAHW_PICO|PAHW_SVP)))
+      PicoIn.AHW |= PAHW_32X;
    ret = PicoStateFP(&state, 1, NULL, state_skip, NULL, state_fseek);
+   PicoIn.AHW = AHW;
    if (ret != 0)
       return 0;
 
-- 
2.39.5