From 19e894a3a9d9aeb0fbb3bf10ead34bed35f15a05 Mon Sep 17 00:00:00 2001
From: Shamus Hammons <jlhamm@acm.org>
Date: Mon, 1 Apr 2013 11:28:58 -0500
Subject: [PATCH] Added FPS counter.

---
 src/cdrom.cpp       | 37 ++++++++++++++++++++++++++++++++-----
 src/gui/mainwin.cpp | 36 ++++++++++++++++++++++++++++++++++++
 src/gui/mainwin.h   |  5 +++++
 3 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/src/cdrom.cpp b/src/cdrom.cpp
index b6279f9..a984c20 100644
--- a/src/cdrom.cpp
+++ b/src/cdrom.cpp
@@ -37,7 +37,7 @@ SB_TIME   equ  BUTCH+$20	; Subcode time and compare enable (D24)
 FIFO_DATA equ  BUTCH+$24	; i2s FIFO data
 I2SDAT1   equ  BUTCH+$24	; i2s FIFO data
 I2SDAT2   equ  BUTCH+$28	; i2s FIFO data
-2C = ?
+          equ  BUTCH+$2C	; CD EEPROM interface
 
 ;
 ; Butch's hardware registers
@@ -112,20 +112,47 @@ $70nn - Set oversampling mode
 
 Commands send through serial bus:
 
-$100 - ? Acknowledge ?
-$130 - ? (Seems to always prefix the $14n commands)
-$140 - Returns ACK (1) (Write to NVRAM?)
+$100 - ? Acknowledge ? (Erase/Write disable)
+$130 - ? (Seems to always prefix the $14n commands) (Erase/Write enable)
+$140 - Returns ACK (1) (Write to NVRAM?) (Write selected register)
 $141 - Returns ACK (1)
 $142 - Returns ACK (1)
 $143 - Returns ACK (1)
 $144 - Returns ACK (1)
 $145 - Returns ACK (1)
-$180 - Returns 16-bit value (NVRAM?)
+$180 - Returns 16-bit value (NVRAM?) (read from EEPROM)
 $181 - Returns 16-bit value
 $182 - Returns 16-bit value
 $183 - Returns 16-bit value
 $184 - Returns 16-bit value
 $185 - Returns 16-bit value
+
+;  The BUTCH interface for the CD-ROM module is a long-word register,
+;   where only the least signifigant 4 bits are used
+;
+eeprom	equ	$DFFF2c			;interface to CD-eeprom
+;
+;  bit3 - busy if 0 after write cmd, or Data In after read cmd 
+;  bit2 - Data Out
+;  bit1 - clock
+;  bit0 - Chip Select (CS)
+;
+;
+;   Commands specific to the National Semiconductor NM93C14
+;
+;
+;  9-bit commands..
+;			 876543210
+eREAD	equ	%110000000		;read from EEPROM
+eEWEN	equ	%100110000		;Erase/write Enable
+eERASE	equ	%111000000		;Erase selected register
+eWRITE	equ	%101000000		;Write selected register
+eERAL	equ	%100100000		;Erase all registers
+eWRAL	equ	%100010000		;Writes all registers
+eEWDS	equ	%100000000		;Erase/Write disable (default)
+
+So... are there $40 words of memory? 128 bytes?
+
 */
 
 // Private function prototypes
diff --git a/src/gui/mainwin.cpp b/src/gui/mainwin.cpp
index 02da8c7..ba2c0dd 100644
--- a/src/gui/mainwin.cpp
+++ b/src/gui/mainwin.cpp
@@ -89,6 +89,12 @@ MainWin::MainWin(bool autoRun): running(true), powerButtonOn(false),
 	for(int i=0; i<8; i++)
 		keyHeld[i] = false;
 
+	// FPS management
+	for(int i=0; i<RING_BUFFER_SIZE; i++)
+		ringBuffer[i] = 0;
+
+	ringBufferPointer = RING_BUFFER_SIZE - 1;
+
 	videoWidget = new GLWidget(this);
 	setCentralWidget(videoWidget);
 	setWindowIcon(QIcon(":/res/vj-icon.png"));
@@ -674,6 +680,36 @@ void MainWin::Timer(void)
 	}
 
 	videoWidget->updateGL();
+
+#if 1
+	// FPS handling
+	// Approach: We use a ring buffer to store timestamps over a given amount
+	// of frames, then sum them to figure out the FPS.
+	uint32_t timestamp = SDL_GetTicks();
+	// This assumes the ring buffer size is a power of 2
+	ringBufferPointer = (ringBufferPointer + 1) & (RING_BUFFER_SIZE - 1);
+	ringBuffer[ringBufferPointer] = timestamp - oldTimestamp;
+	uint32_t elapsedTime = 0;
+
+	for(uint32_t i=0; i<RING_BUFFER_SIZE; i++)
+		elapsedTime += ringBuffer[i];
+
+	// elapsedTime must be non-zero
+	if (elapsedTime == 0)
+		elapsedTime = 1;
+
+#if 0
+	float framesPerSecond = ((float)RING_BUFFER_SIZE / (float)elapsedTime) * 1000.0;
+	statusBar()->showMessage(QString("%1 FPS").arg(framesPerSecond));
+#else
+	// This is in frames per 10 seconds, so we can have 1 decimal
+	uint32_t framesPerSecond = (uint32_t)(((float)RING_BUFFER_SIZE / (float)elapsedTime) * 10000.0);
+	uint32_t fpsIntegerPart = framesPerSecond / 10;
+	uint32_t fpsDecimalPart = framesPerSecond % 10;
+	statusBar()->showMessage(QString("%1.%2 FPS").arg(fpsIntegerPart).arg(fpsDecimalPart));
+#endif
+	oldTimestamp = timestamp;
+#endif
 }
 
 
diff --git a/src/gui/mainwin.h b/src/gui/mainwin.h
index 9efddfd..c87ce99 100644
--- a/src/gui/mainwin.h
+++ b/src/gui/mainwin.h
@@ -12,6 +12,8 @@
 #include <QtGui>
 #include "tom.h"
 
+#define RING_BUFFER_SIZE 32
+
 // Forward declarations
 class GLWidget;
 class AboutWindow;
@@ -100,6 +102,9 @@ class MainWin: public QMainWindow
 		bool fullScreen;
 	public:
 		bool plzDontKillMyComputer;
+		uint32_t oldTimestamp;
+		uint32_t ringBufferPointer;
+		uint32_t ringBuffer[RING_BUFFER_SIZE];
 	private:
 		QPoint mainWinPosition;
 //		QSize mainWinSize;
-- 
2.37.2