System: Fix loading of EXEs with sp=0 (leave unchanged)

src/core/bios.cpp

@@ -168,11 +168,30 @@ bool PatchBIOSForEXE(Image& image, u32 r_pc, u32 r_gp, u32 r_sp, u32 r_fp)
   PatchBIOS(image, 0xBFC06FF4, UINT32_C(0x35080000) | (r_pc & UINT32_C(0xFFFF))); // ori $t0, $t0, (r_pc & 0xFFFF)
   PatchBIOS(image, 0xBFC06FF8, UINT32_C(0x3C1C0000) | r_gp >> 16);                // lui $gp, (r_gp >> 16)
   PatchBIOS(image, 0xBFC06FFC, UINT32_C(0x379C0000) | (r_gp & UINT32_C(0xFFFF))); // ori $gp, $gp, (r_gp & 0xFFFF)
-  PatchBIOS(image, 0xBFC07000, UINT32_C(0x3C1D0000) | r_sp >> 16);                // lui $sp, (r_sp >> 16)
-  PatchBIOS(image, 0xBFC07004, UINT32_C(0x37BD0000) | (r_sp & UINT32_C(0xFFFF))); // ori $sp, $sp, (r_sp & 0xFFFF)
-  PatchBIOS(image, 0xBFC07008, UINT32_C(0x3C1E0000) | r_fp >> 16);                // lui $fp, (r_fp >> 16)
-  PatchBIOS(image, 0xBFC0700C, UINT32_C(0x01000008));                             // jr $t0
-  PatchBIOS(image, 0xBFC07010, UINT32_C(0x37DE0000) | (r_fp & UINT32_C(0xFFFF))); // ori $fp, $fp, (r_fp & 0xFFFF)
+
+  if (r_sp != 0)
+  {
+    PatchBIOS(image, 0xBFC07000, UINT32_C(0x3C1D0000) | r_sp >> 16);                // lui $sp, (r_sp >> 16)
+    PatchBIOS(image, 0xBFC07004, UINT32_C(0x37BD0000) | (r_sp & UINT32_C(0xFFFF))); // ori $sp, $sp, (r_sp & 0xFFFF)
+  }
+  else
+  {
+    PatchBIOS(image, 0xBFC07000, UINT32_C(0x00000000)); // nop
+    PatchBIOS(image, 0xBFC07004, UINT32_C(0x00000000)); // nop
+  }
+  if (r_fp != 0)
+  {
+    PatchBIOS(image, 0xBFC07008, UINT32_C(0x3C1E0000) | r_fp >> 16);                // lui $fp, (r_fp >> 16)
+    PatchBIOS(image, 0xBFC0700C, UINT32_C(0x01000008));                             // jr $t0
+    PatchBIOS(image, 0xBFC07010, UINT32_C(0x37DE0000) | (r_fp & UINT32_C(0xFFFF))); // ori $fp, $fp, (r_fp & 0xFFFF)
+  }
+  else
+  {
+    PatchBIOS(image, 0xBFC07008, UINT32_C(0x00000000)); // nop
+    PatchBIOS(image, 0xBFC0700C, UINT32_C(0x01000008)); // jr $t0
+    PatchBIOS(image, 0xBFC07010, UINT32_C(0x00000000)); // nop
+  }
+
   return true;
 }
 

src/core/system.cpp

@@ -386,9 +386,9 @@ bool System::LoadEXE(const char* filename, std::vector<u8>& bios_image)
   std::fclose(fp);
 
   // patch the BIOS to jump to the executable directly
-  const u32 r_pc = header.load_address;
+  const u32 r_pc = header.initial_pc;
   const u32 r_gp = header.initial_gp;
-  const u32 r_sp = header.initial_sp_base;
+  const u32 r_sp = header.initial_sp_base + header.initial_sp_offset;
   const u32 r_fp = header.initial_sp_base + header.initial_sp_offset;
   return BIOS::PatchBIOSForEXE(bios_image, r_pc, r_gp, r_sp, r_fp);
 }