From b79a6744a0798ea7277b55164813be9c8747a4a3 Mon Sep 17 00:00:00 2001
From: "Satoshi N. M" <snmatsutake@yahoo.co.jp>
Date: Mon, 15 Jan 2018 14:23:12 -0800
Subject: [PATCH] Merge emulated frequency measurement into ^T command

---
 README.md  |  3 +--
 src/main.c | 35 +++++++++++++++--------------------
 2 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/README.md b/README.md
index ca41343..68c151a 100644
--- a/README.md
+++ b/README.md
@@ -22,10 +22,9 @@ Special commands built-in, not passed to the ACIA and 6502:
 | --------- | ------ |
 | ^V | Show `pill_6502` version |
 | ^P | Pause/resume 6502 processor execution |
-| ^F | Show frequency |
 | ^R | Reset the 6502 processor (also reset on USB reset) |
 | ^E | Local echo toggle, off by default |
-| ^T | Show clock ticks and instruction count |
+| ^T | Show clock ticks, instruction count, and frequency since last ^T |
 | ^G | Show help |
 
 Intended to be somewhat compatible with [Grant Searle's Simple6502](http://searle.hostei.com/grant/6502/Simple6502.html),
diff --git a/src/main.c b/src/main.c
index 5928418..7916d19 100644
--- a/src/main.c
+++ b/src/main.c
@@ -113,24 +113,6 @@ char *process_serial_command(char b) {
 		paused = !paused;
 		return paused ? "paused" : "resumed";
 	} else if (b == '\x06') { // ^F
-		static uint32_t last_ticks = 0;
-		static uint32_t last_millis = 0;
-		if (last_ticks == 0) {
-			last_ticks = clockticks6502;
-			last_millis = millis;
-
-			return "press ^F again to measure frequency";
-		}
-
-		uint32_t hz = (clockticks6502 - last_ticks) * 1000 / (millis - last_millis);
-
-		static char buf[64];
-		snprintf(buf, sizeof(buf), "%ld Hz", hz);
-
-		last_ticks = clockticks6502;
-		last_millis = millis;
-
-		return buf;
 	} else if (b == '\x12') { // ^R
 		reset6502();
 		paused = false;
@@ -139,11 +121,24 @@ char *process_serial_command(char b) {
 		local_echo = !local_echo;
 		return local_echo ? "local echo enabled" : "local echo disabled";
 	} else if (b == '\x14') { // ^T
+		static uint32_t last_ticks = 0;
+		static uint32_t last_millis = 0;
+		uint32_t hz = 0;
+		if (last_ticks != 0) {
+			uint32_t elapsed_ticks = clockticks6502 - last_ticks;
+			uint32_t elapsed_millis = millis - last_millis;
+
+			if (elapsed_millis != 0) hz = elapsed_ticks * 1000 / elapsed_millis;
+		}
+
+		last_ticks = clockticks6502;
+		last_millis = millis;
+
 		static char buf[64];
-		snprintf(buf, sizeof(buf), "%ld ticks\r\n%ld instructions", clockticks6502, instructions);
+		snprintf(buf, sizeof(buf), "%ld ticks\r\n%ld instructions\r\n%ld Hz", clockticks6502, instructions, hz);
 		return buf;
 	} else if (b == '\x07') { // ^G
-		return "^V=version ^R=reset ^E=echo ^P=pause ^F=freq ^T=ticks ^G=help";
+		return "^V=version ^R=reset ^E=echo ^P=pause ^T=timing ^G=help";
 	}
 
 	return NULL;