From 76cefb1e37fc228a4b7adbd69190fd9da58d924c Mon Sep 17 00:00:00 2001
From: nmlgc <nmlgc@nmlgc.net>
Date: Mon, 15 Feb 2021 14:54:13 +0100
Subject: [PATCH] [Decompilation] [th05] pi_load()

That assembly is *worse* than what you would have gotten out of your
1994 C++ compiler with the 386 code generation switch!

Part of P0134, funded by [Anonymous].
---
 th05/formats/pi_cpp_2.cpp | 23 +++++++++++++++++++++++
 th05/formats/pi_load.asm  | 29 -----------------------------
 th05_maine.asm            |  2 +-
 th05_op.asm               |  2 +-
 4 files changed, 25 insertions(+), 31 deletions(-)
 delete mode 100644 th05/formats/pi_load.asm

diff --git a/th05/formats/pi_cpp_2.cpp b/th05/formats/pi_cpp_2.cpp
index 83dc8141..166a2006 100644
--- a/th05/formats/pi_cpp_2.cpp
+++ b/th05/formats/pi_cpp_2.cpp
@@ -18,6 +18,29 @@ void pascal near pi_put_8_rowloop(
 	screen_x_t left, vram_y_t top, pixel_t w, size_t stride_packed
 );
 
+int DEFCONV pi_load(int slot, const char *fn)
+{
+	_DI = slot;
+	/* TODO: Replace with the decompiled call
+	 * 	pi_free(slot);
+	 * once the segmentation allows us to, if ever */
+	__asm { push di; push cs; call near ptr pi_free; }
+
+	/* Actually, also replace this garbage with simply
+	 * 	return graph_pi_load_pack(fn, &pi_headers[slot], &pi_buffers[slot]);
+	 * Even Turbo C++ can generate better code than *that*. */
+	_SI = _DI;
+	_SI <<= 2;	// *= sizeof(void far *)
+	_SI += reinterpret_cast<uint16_t>(pi_buffers);
+	imul_di(sizeof(PiHeader));
+	_DI += reinterpret_cast<uint16_t>(pi_headers);
+	return graph_pi_load_pack(
+		fn,
+		reinterpret_cast<PiHeader near *>(_DI),
+		reinterpret_cast<void far *near *>(_SI)
+	);
+}
+
 void DEFCONV pi_put_8(screen_x_t left, vram_y_t top, int slot)
 {
 	#define rowloop_func __asm { \
diff --git a/th05/formats/pi_load.asm b/th05/formats/pi_load.asm
deleted file mode 100644
index 0e4aef44..00000000
--- a/th05/formats/pi_load.asm
+++ /dev/null
@@ -1,29 +0,0 @@
-public PI_LOAD
-func pi_load
-	; (PASCAL calling convention, parameter list needs to be reversed here)
-	arg @@fn:ptr, @@slot:word
-
-	push	bp
-	mov	bp, sp
-	push	si
-	push	di
-	mov	di, @@slot
-	push	di
-	call	pi_free
-	mov	si, di
-	shl	si, 2
-	add	si, offset _pi_buffers
-	imul	di, size PiHeader
-	add	di, offset _pi_headers
-	push	word ptr @@fn+2
-	push	word ptr @@fn
-	push	ds
-	push	di
-	push	ds
-	push	si
-	call	graph_pi_load_pack
-	pop	di
-	pop	si
-	pop	bp
-	ret	6
-endfunc
diff --git a/th05_maine.asm b/th05_maine.asm
index 6528702b..0bd31b55 100644
--- a/th05_maine.asm
+++ b/th05_maine.asm
@@ -7539,7 +7539,7 @@ include th04/bgimage_put_rect.asm
 include th05/snd/load.asm
 include th05/snd/kajaint.asm
 include th05/formats/pi_put_masked.asm
-include th05/formats/pi_load.asm
+	extern PI_LOAD:proc
 	extern PI_PUT_8:proc
 	extern PI_PUT_QUARTER_8:proc
 	extern PI_PALETTE_APPLY:proc
diff --git a/th05_op.asm b/th05_op.asm
index e1e46976..fe3f4a33 100644
--- a/th05_op.asm
+++ b/th05_op.asm
@@ -2544,7 +2544,7 @@ include th04/bgimage_put_rect.asm
 include th05/snd/load.asm
 include th05/snd/kajaint.asm
 include th05/formats/pi_put_masked.asm
-include th05/formats/pi_load.asm
+	extern PI_LOAD:proc
 	extern PI_PUT_8:proc
 	extern PI_PALETTE_APPLY:proc
 	extern PI_FREE:proc