From 5f934376d5ea8362f19de0bccbfa945fc60d72a0 Mon Sep 17 00:00:00 2001
From: ayuanx <ayuanx@gmail.com>
Date: Thu, 8 Aug 2024 01:04:02 +1000
Subject: [PATCH] Small compiler optimizations

---
 README.md   |  3 +++
 ogg-winmm.c |  2 +-
 player.c    | 22 +++++++++++++---------
 stubs.c     | 16 ++++++++--------
 4 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/README.md b/README.md
index 487c2b8..e14dc1d 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,9 @@ NOTE: It actually can also work on Win95/98 if you follow the extra procedure be
 
 # Revisions:
 
+v.2024.08.08
+- Small compiler optimizations.
+
 v.2024.03.21
 - Fix the truncation at the end of each song ranging from 1ms to 500ms.
 
diff --git a/ogg-winmm.c b/ogg-winmm.c
index 04516dc..f9dcc04 100644
--- a/ogg-winmm.c
+++ b/ogg-winmm.c
@@ -51,7 +51,7 @@ struct play_info
 struct track_info tracks[MAX_TRACKS+1]; // Track 0 is reserved.
 struct play_info info = {0};
 
-DWORD thread = 0; // Needed for Win85/98 compatibility
+DWORD thread = 0; // Needed for Win95/98 compatibility
 HANDLE player = NULL;
 HANDLE event = NULL;
 HWND window = NULL;
diff --git a/player.c b/player.c
index dad4986..4f717b5 100644
--- a/player.c
+++ b/player.c
@@ -11,7 +11,7 @@
 bool		plr_run			= false;
 bool		plr_bsy			= false;
 unsigned int	plr_len			= 0;
-float		plr_vol[2]		= {100.0, 100.0}; // Left, Right
+float		plr_vol[2]		= {1.0, 1.0}; // Left, Right
 
 HWAVEOUT	plr_hw	 		= NULL;
 HANDLE		plr_ev  		= NULL;
@@ -24,10 +24,10 @@ char		plr_buf[WAV_BUF_CNT][WAV_BUF_LEN] __attribute__ ((aligned(4)));
 
 void plr_volume(int vol_l, int vol_r)
 {
-	if (vol_l < 0 || vol_l > 99) plr_vol[0] = 100.0;
+	if (vol_l < 0 || vol_l > 99) plr_vol[0] = 1.0;
 	else plr_vol[0] = vol_l / 100.0;
 
-	if (vol_r < 0 || vol_r > 99) plr_vol[1] = 100.0;
+	if (vol_r < 0 || vol_r > 99) plr_vol[1] = 1.0;
 	else plr_vol[1] = vol_r / 100.0;
 }
 
@@ -102,8 +102,8 @@ int plr_play(const char *path, unsigned int from, unsigned int to)
 
 	if (from == -1) plr_len = 0; 
 	else {
-		if (from) ov_time_seek(&plr_vf, (double)from / 1000);
-		plr_len = to != -1 ? (unsigned int)ceil((to - from) / 1000.0 * vi->rate) * 2 * vi->channels : -1; // heed alignment 
+		if (from) ov_time_seek(&plr_vf, from * 0.001);
+		plr_len = to != -1 ? (unsigned int)ceil((to - from) * 0.001 * vi->rate) * 2 * vi->channels : -1; // heed alignment 
 	}
 
 	plr_run = true;
@@ -180,11 +180,15 @@ int plr_pump()
 		plr_len -= pos;
 
 		/* volume control, kinda nasty */
-		if (plr_vol[0] != 100.0 || plr_vol[1] != 100.0) {
+		if (plr_vol[0] != 1.0 || plr_vol[1] != 1.0) {
 			short *sbuf = (short *)buf;
 			for (int j = 0, end = pos / 2; j < end; j+=2) {
-				if (plr_vol[0] != 100.0) sbuf[j] *= plr_vol[0];
-				if (plr_vol[1] != 100.0) sbuf[j+1] *= plr_vol[1];
+				// Surprisingly speedwise (fast > slow): float multiplication > float divison >> int multiplication > int division.
+				// Also remove branching for better compiler SIMD/loop unrolling optimization.
+				//if (plr_vol[0] != 1.0) sbuf[j] *= plr_vol[0];
+				//if (plr_vol[1] != 1.0) sbuf[j+1] *= plr_vol[1];
+				sbuf[j] *= plr_vol[0];
+				sbuf[j+1] *= plr_vol[1];
 			}
 		}
 
@@ -215,7 +219,7 @@ int plr_pump()
 	return 1;
 }
 
-/* TODO: */
+/* Not needed: */
 /*
    int plr_seek(int sec)
    {
diff --git a/stubs.c b/stubs.c
index 767b2d5..e17505c 100644
--- a/stubs.c
+++ b/stubs.c
@@ -3,14 +3,14 @@
 #include <ctype.h>
 #include "player.h"
 
-static float midiVol = 100.0;
-static float waveVol = 100.0;
+static float midiVol = 1.0;
+static float waveVol = 1.0;
 static int waveBits = -1;
 
 static HINSTANCE realWinmmDLL = NULL;
 
-void stub_midivol(int vol) { midiVol = vol < 0 || vol > 99  ? 100.0 : vol / 100.0; }
-void stub_wavevol(int vol) { waveVol = vol < 0 || vol > 99  ? 100.0 : vol / 100.0; }
+void stub_midivol(int vol) { midiVol = vol < 0 || vol > 99  ? 1.0 : vol / 100.0; }
+void stub_wavevol(int vol) { waveVol = vol < 0 || vol > 99  ? 1.0 : vol / 100.0; }
 
 void unloadRealDLL()
 {
@@ -43,7 +43,7 @@ MMRESULT WINAPI fake_midiStreamOut(HMIDISTRM a0, LPMIDIHDR a1, UINT a2)
 		funcp = (void*)GetProcAddress(loadRealDLL(), "midiStreamOut");
 
 #ifdef MIDI_VELOCITY_SCALING
-	if (midiVol != 100.0 && a1 && a1->lpData) {
+	if (midiVol != 1.0 && a1 && a1->lpData) {
 		for (int i = 0, j = a1->dwBytesRecorded; i < j; i += sizeof(DWORD)*3) {
 			MIDIEVENT *pe = (MIDIEVENT *)(a1->lpData + i);
 			if (pe->dwEvent & MEVT_F_LONG) {
@@ -86,7 +86,7 @@ MMRESULT WINAPI fake_waveOutWrite(HWAVEOUT a0, LPWAVEHDR a1, UINT a2)
 		funcp = (void*)GetProcAddress(loadRealDLL(), "waveOutWrite");
 
 	/* let owr own OGG wave pass through */
-	if ((waveVol != 100.0 || midiVol != 100.0 ) && a1 && a1->lpData && a1->dwUser != 0xCDDA7777) {
+	if ((waveVol != 1.0 || midiVol != 1.0 ) && a1 && a1->lpData && a1->dwUser != 0xCDDA7777) {
 		/* Windows is f**ked up. MIDI synth driver converts MIDI to WAVE and then calls winmm.waveOutWrite!!! */
 		void *addr = __builtin_return_address(0);
 		char caller[MAX_PATH];
@@ -94,13 +94,13 @@ MMRESULT WINAPI fake_waveOutWrite(HWAVEOUT a0, LPWAVEHDR a1, UINT a2)
 		VirtualQuery(addr, &mbi, sizeof(MEMORY_BASIC_INFORMATION));
 		GetModuleFileName(mbi.AllocationBase, caller, MAX_PATH);
 
-		float vol = 100.0;
+		float vol = 1.0;
 		char *pos = strrchr(caller, '\\');
 		/* Mixer: msacm32.drv */
 		if (strstr(pos, "wdmaud.drv")) vol = midiVol;
 		else if (!strstr(pos, ".drv")) vol = waveVol;
 
-		if (vol != 100.0) {
+		if (vol != 1.0) {
 			short *wave16;
 			char *wave8;
 			switch (waveBits) {