From 0c1c47d5787626380f5ceeb6d1d2ae44c44a0b6e Mon Sep 17 00:00:00 2001
From: Oskar <oskar@winkels.berlin>
Date: Tue, 30 Mar 2021 23:07:10 +0200
Subject: [PATCH] Add microcontroller-friendly version

---
 klock4_uc.c | 154 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 154 insertions(+)
 create mode 100644 klock4_uc.c

diff --git a/klock4_uc.c b/klock4_uc.c
new file mode 100644
index 0000000..a13c48c
--- /dev/null
+++ b/klock4_uc.c
@@ -0,0 +1,154 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+#include <time.h>
+#include <math.h>
+
+#define ROWS 10
+#define COLS 11
+
+const unsigned char TEXT[] = "\
+ESXISTXFUNF\
+ZEHNZWANZIG\
+DREIVIERTEL\
+VORGESTNACH\
+HALBXELFUNF\
+EINSXLEZWEI\
+DREIXTXVIER\
+SECHSXXACHT\
+SIEBENZWOLF\
+ZEHNEUNXUHR";
+
+typedef struct {uint8_t start; uint16_t len;} word_t;
+
+#define ES			((word_t) {.start=  0, .len=2})
+#define IST			((word_t) {.start=  3, .len=3})
+#define FUNF_PRE	((word_t) {.start=  7, .len=4})
+#define ZEHN_PRE	((word_t) {.start= 11, .len=4})
+#define ZWANZIG		((word_t) {.start= 15, .len=7})
+#define VIERTEL		((word_t) {.start= 26, .len=7})
+#define VOR			((word_t) {.start= 33, .len=3})
+#define NACH		((word_t) {.start= 40, .len=4})
+#define HALB		((word_t) {.start= 44, .len=4})
+#define ELF			((word_t) {.start= 49, .len=3})
+#define FUNF_UHR	((word_t) {.start= 51, .len=4})
+#define EINS		((word_t) {.start= 55, .len=4})
+#define ZWEI		((word_t) {.start= 62, .len=4})
+#define DREI		((word_t) {.start= 66, .len=4})
+#define VIER		((word_t) {.start= 73, .len=4})
+#define SECHS		((word_t) {.start= 77, .len=5})
+#define ACHT		((word_t) {.start= 84, .len=4})
+#define SIEBEN		((word_t) {.start= 88, .len=6})
+#define ZWOLF		((word_t) {.start= 94, .len=5})
+#define ZEHN_UHR	((word_t) {.start= 99, .len=4})
+#define NEUN		((word_t) {.start=102, .len=4})
+#define UHR			((word_t) {.start=107, .len=3})
+
+word_t HOURS[] = {
+	ZWOLF, EINS, ZWEI, DREI, VIER, FUNF_UHR,
+	SECHS, SIEBEN, ACHT, NEUN, ZEHN_UHR, ELF
+};
+word_t PARTS[] = {
+	UHR, FUNF_PRE, ZEHN_PRE, VIERTEL,
+	ZWANZIG, FUNF_PRE, HALB
+};
+
+
+uint8_t active[ROWS*COLS] = {0};
+
+void set(word_t word) {
+	for (unsigned int i = word.start; i < word.start + word.len; i++)
+		active[i] = 1;
+}
+
+void reset(void) {
+	memset(&active, 0, sizeof(active));
+	set(ES);
+	set(IST);
+}
+
+
+void settime(time_t ts) {
+
+	unsigned int second = ts % 60;
+
+	unsigned int minute = (ts / 60) % 60;
+	float fminute = (float) minute + (float) second / 60;
+	minute = 5 * (unsigned int) roundf(fminute / 5);
+
+	unsigned int daylight_savings = 1;
+	unsigned int hour   = (ts / (60*60) + 1 + daylight_savings) % 12;
+
+	//printf("%02d:%02d\n", hour, minute);
+
+	int before = 0;
+
+	if (minute >= 25) {
+		hour = (hour+1) % 12;
+		before = 1;
+		minute = 60-minute;
+		if (minute == 35) {
+			minute = 25;
+			before = 0;
+		}
+	}
+
+	//printf("%02d %s %02d\n", minute, before ? "vor" : "nach", hour);
+
+	if (minute == 25)
+		before = !before;
+
+	reset();
+
+	if (minute != 0 && minute != 30)
+		set(before ? VOR : NACH);
+
+	set(HOURS[hour]);
+	set(PARTS[minute/5]);
+
+	if (minute/5 == 5)
+		set(HALB); // '5 before half' requires additional set
+
+}
+
+
+void dump() {
+
+	const char WHITE[] = "\033[1;37m";
+	const char  GRAY[] = "\033[0;30m";
+
+	for (int i = 0; i < ROWS*COLS; i++) {
+
+		int col = i % COLS;
+		if (col == 0)
+			printf("\n ");
+
+		const char* color = active[i] ? WHITE : GRAY;
+
+		printf("  %s%c", color, TEXT[i]);
+
+	}
+
+	#define RESET_COLORS "\033[0m"
+	printf(RESET_COLORS "\n");
+
+}
+
+int main() {
+
+	time_t ts = time(NULL);
+
+	while (1) {
+		printf("\033c");
+		ts = time(NULL);
+		settime(ts);
+		dump();
+
+		sleep(5);
+	};
+
+	return 0;
+
+}