create runner game

Makefile

@@ -1,11 +0,0 @@
-all : flash
-
-TARGET:=oled_gol
-CH32V003FUN:=../ch32v003fun/ch32v003fun
-
-include ../ch32v003fun/ch32v003fun/ch32v003fun.mk
-
-flash : build
-	gdb-multiarch -x gdbinit -ex 'load' -ex 'detach' -ex 'quit' $(TARGET).elf
-clean : cv_clean
-

gol/Makefile

@@ -0,0 +1,11 @@
+all : flash
+
+TARGET:=gol
+CH32V003FUN:=../../ch32v003fun/ch32v003fun
+
+include ../../ch32v003fun/ch32v003fun/ch32v003fun.mk
+
+flash : build
+	gdb-multiarch -x ../gdbinit -ex 'load' -ex 'detach' -ex 'quit' $(TARGET).elf
+clean : cv_clean
+

gol/ssd1306.h

@@ -480,7 +480,7 @@ uint8_t ssd1306_init(void)
 	}
 
 	// clear display
-	// ssd1306_setbuf(0);
+	ssd1306_setbuf(0);
 	ssd1306_refresh();
 
 	return 0;

soweli/Makefile

@@ -0,0 +1,11 @@
+all : flash
+
+TARGET:=soweli
+CH32V003FUN:=../../ch32v003fun/ch32v003fun
+
+include ../../ch32v003fun/ch32v003fun/ch32v003fun.mk
+
+flash : build
+	gdb-multiarch -x ../gdbinit -ex 'load' -ex 'detach' -ex 'quit' $(TARGET).elf
+clean : cv_clean
+

soweli/data.h

@@ -0,0 +1,80 @@
+#define OBSTACLE_TYPES 5
+
+const unsigned char soweli_a[8] = {
+	0b01111111,
+	0b10000000,
+	0b10101000,
+	0b10101000,
+	0b10000000,
+	0b01010101,
+	0b01010000,
+	0b01010000,
+};
+
+const unsigned char soweli_b[8] = {
+	0b01111111,
+	0b10000000,
+	0b10101000,
+	0b10101000,
+	0b10000000,
+	0b01010101,
+	0b00000101,
+	0b00000101,
+};
+
+const unsigned char obstacle_sprites[OBSTACLE_TYPES][8] = {
+	{
+		0b00000000,
+		0b00000000,
+		0b01010101,
+		0b01010100,
+		0b11111110,
+		0b01010100,
+		0b01010101,
+		0b00000000,
+	},
+	{
+		0b00000000,
+		0b00000000,
+		0b00000000,
+		0b00000000,
+
+		0b00111100,
+		0b01100110,
+		0b11000011,
+		0b10000001,
+	},
+	{
+		0b00000000,
+		0b00000000,
+		0b00000000,
+		0b00000000,
+		0b11111111,
+		0b01000010,
+		0b01000010,
+		0b01000010,
+	},
+	{
+		0b01000010,
+		0b00011000,
+		0b00100100,
+		0b01111110,
+		0b00100100,
+		0b01111110,
+		0b00100100,
+		0b00011000,
+	},
+	{
+		0b00000000,
+		0b00000000,
+		0b00000000,
+		0b00011000,
+		0b00011000,
+		0b00011000,
+		0b00011000,
+		0b00111100,
+	},
+};
+
+const unsigned char obstacle_heights[OBSTACLE_TYPES] = {6, 4, 4, 8, 5};
+const unsigned char obstacle_widths[OBSTACLE_TYPES] = {8, 8, 8, 7, 5};

soweli/funconfig.h

@@ -0,0 +1,7 @@
+#ifndef _FUNCONFIG_H
+#define _FUNCONFIG_H
+
+#define CH32V003           1
+
+#endif
+

soweli/soweli.c

@@ -0,0 +1,255 @@
+
+#define SSD1306_128X32
+#include "ch32v003fun.h"
+#include <stdio.h>
+#include "ssd1306_i2c.h"
+#include "ssd1306.h"
+
+#include "data.h"
+
+#define PIN_LED PC4
+#define PIN_BTN PC7
+
+// #define JUMP_POWER 48
+// #define GRAVITY 3
+#define JUMP_POWER 36
+#define GRAVITY 2
+#define SCROLL_SPEED 1
+#define FRAME_DELAY 1000 / 60
+#define SCORE_DIGITS 4
+#define RUN_ANIM_SPEED 4
+#define PLAYER_X 16
+#define Y_PRECISION 4
+
+u32 time = 0;
+u16 score = 0;
+u16 highscore = 0;
+s16 player_y = 0;
+s16 player_vel = 0;
+#define MAX_OBSTACLES 16
+u8 obstacle_positions[MAX_OBSTACLES];
+u8 obstacle_types[MAX_OBSTACLES]; // todo
+u8 obstacle_count = 0;
+u8 is_running = 1;
+u8 time_to_obstacle = 0;
+
+uint32_t lfsr = 1; // PRNG state
+
+u8 rand8();
+void update();
+void render();
+void restart();
+
+int main()
+{
+	SystemInit();
+	funGpioInitAll();
+	funPinMode(PIN_LED, GPIO_CFGLR_OUT_10Mhz_PP);
+	funPinMode(PIN_BTN, GPIO_CFGLR_IN_PUPD);
+
+	ssd1306_i2c_init();
+	ssd1306_init();
+
+	restart();
+	while (1)
+	{
+		ssd1306_refresh();
+
+		if (is_running)
+			update();
+		render();
+		time += 1;
+
+		if (funDigitalRead(PIN_BTN))
+		{
+			if (is_running)
+			{
+				if (player_y == 0 && player_vel == 0)
+				{
+					player_vel = JUMP_POWER;
+				}
+			}
+			else
+				restart();
+		}
+		if (is_running == 0)
+		{
+			funDigitalWrite(PIN_LED, (time >> 2) & 1);
+		}
+		else
+		{
+			funDigitalWrite(PIN_LED, FUN_LOW);
+		}
+		Delay_Ms(FRAME_DELAY);
+	}
+}
+
+void restart()
+{
+	lfsr = SysTick->CNT;
+	is_running = 1;
+	player_vel = 0;
+	player_y = 0;
+	obstacle_count = 0;
+	time_to_obstacle = 0;
+	if (highscore < score)
+		highscore = score;
+	score = 0;
+}
+
+void remove_obstacle()
+{
+	if (obstacle_count == 0)
+		return;
+	for (u8 i = 1; i < obstacle_count; i++)
+	{
+		obstacle_positions[i - 1] = obstacle_positions[i];
+		obstacle_types[i - 1] = obstacle_types[i];
+	}
+	obstacle_count--;
+}
+
+void spawn_obstacle(u8 pos)
+{
+	if (obstacle_count >= MAX_OBSTACLES)
+		return;
+	obstacle_positions[obstacle_count] = pos;
+	obstacle_types[obstacle_count] = rand8() % OBSTACLE_TYPES;
+	obstacle_count++;
+}
+
+void update()
+{
+	score += (time & 4) != 0;
+	if (player_vel != 0 || player_y != 0)
+	{
+		player_vel -= GRAVITY;
+		player_y += player_vel;
+		if (player_y < 0)
+		{
+			player_y = 0;
+			player_vel = 0;
+		}
+	}
+	for (u8 i = 0; i < obstacle_count; i++)
+	{
+		obstacle_positions[i] -= SCROLL_SPEED;
+		u8 type = obstacle_types[i];
+		u8 dist_x = gfx_abs((s16)obstacle_positions[i] - (s16)PLAYER_X);
+		if (dist_x < obstacle_widths[type] && (player_y >> Y_PRECISION) < obstacle_heights[type])
+		{
+			is_running = 0;
+		}
+	}
+	if (obstacle_count > 0 && obstacle_positions[0] == 0)
+	{
+		remove_obstacle();
+	}
+	if (time_to_obstacle < 5)
+	{
+		u8 count = 1 + (rand8() & rand8() & 1) + (rand8() & rand8() & rand8() & rand8() & 1);
+		for (u8 i = 0; i < count; i++)
+		{
+			spawn_obstacle(128 + i * 8);
+		}
+		time_to_obstacle = (rand8() & 31) + 50;
+	}
+	time_to_obstacle -= 1;
+}
+
+void render_digit(u8 digit, u8 x, u8 y)
+{
+	const u16 digit_font[] = {
+		0b111101101101111, // 0
+		0b010110010010111, // 1
+		0b111001111100111, // 2
+		0b111001111001111, // 3
+		0b101101111001001, // 4
+		0b111100111001111, // 5
+		0b111100111101111, // 6
+		0b111001001001001, // 7
+		0b111101111101111, // 8
+		0b111101111001111, // 9
+	};
+	u16 pixels = digit_font[digit];
+
+	ssd1306_drawPixel(x + 0, y + 0, (pixels >> 14) & 1);
+	ssd1306_drawPixel(x + 1, y + 0, (pixels >> 13) & 1);
+	ssd1306_drawPixel(x + 2, y + 0, (pixels >> 12) & 1);
+	ssd1306_drawPixel(x + 0, y + 1, (pixels >> 11) & 1);
+	ssd1306_drawPixel(x + 1, y + 1, (pixels >> 10) & 1);
+	ssd1306_drawPixel(x + 2, y + 1, (pixels >> 9) & 1);
+	ssd1306_drawPixel(x + 0, y + 2, (pixels >> 8) & 1);
+	ssd1306_drawPixel(x + 1, y + 2, (pixels >> 7) & 1);
+	ssd1306_drawPixel(x + 2, y + 2, (pixels >> 6) & 1);
+	ssd1306_drawPixel(x + 0, y + 3, (pixels >> 5) & 1);
+	ssd1306_drawPixel(x + 1, y + 3, (pixels >> 4) & 1);
+	ssd1306_drawPixel(x + 2, y + 3, (pixels >> 3) & 1);
+	ssd1306_drawPixel(x + 0, y + 4, (pixels >> 2) & 1);
+	ssd1306_drawPixel(x + 1, y + 4, (pixels >> 1) & 1);
+	ssd1306_drawPixel(x + 2, y + 4, (pixels >> 0) & 1);
+}
+
+void render_number(u32 s, u8 x, u8 y, u8 digits)
+{
+	u8 painter_x = x + digits * 4;
+	u32 val = s;
+
+	for (int i = 0; i < digits; i++)
+	{
+		u8 digit = val % 10;
+		render_digit(digit, painter_x, y);
+		val /= 10;
+		painter_x -= 4;
+	}
+}
+
+void render()
+{
+	ssd1306_setbuf(0);
+	ssd1306_drawFastHLine(0, 31, 128, 1);
+
+	render_number(score, 0, 0, SCORE_DIGITS);
+	render_number(highscore, 0, 6, SCORE_DIGITS);
+	// render_number(obstacle_count, 20, 0, 2);
+	// render_number(abs(player_vel), 30, 0, 2);
+	// render_number(time_to_obstacle, 20, 6, 3);
+
+	for (u8 i = 0; i < obstacle_count; i++)
+	{
+		u8 type = obstacle_types[i];
+		ssd1306_drawImage(obstacle_positions[i], 31 - 8, obstacle_sprites[type], 8, 8, 0);
+	}
+
+	if (time & RUN_ANIM_SPEED && is_running)
+		ssd1306_drawImage(PLAYER_X, 31 - (player_y >> Y_PRECISION) - 8, soweli_a, 8, 8, 0);
+	else
+		ssd1306_drawImage(PLAYER_X, 31 - (player_y >> Y_PRECISION) - 8, soweli_b, 8, 8, 0);
+}
+
+/* White Noise Generator State */
+#define NOISE_BITS 8
+#define NOISE_MASK ((1 << NOISE_BITS) - 1)
+#define NOISE_POLY_TAP0 31
+#define NOISE_POLY_TAP1 21
+#define NOISE_POLY_TAP2 1
+#define NOISE_POLY_TAP3 0
+/*
+ * random byte generator, taken from ch32v003fun examples
+ */
+uint8_t rand8(void)
+{
+	uint8_t bit;
+	uint32_t new_data;
+
+	for (bit = 0; bit < NOISE_BITS; bit++)
+	{
+		new_data = ((lfsr >> NOISE_POLY_TAP0) ^
+					(lfsr >> NOISE_POLY_TAP1) ^
+					(lfsr >> NOISE_POLY_TAP2) ^
+					(lfsr >> NOISE_POLY_TAP3));
+		lfsr = (lfsr << 1) | (new_data & 1);
+	}
+
+	return lfsr & NOISE_MASK;
+}

soweli/ssd1306.h

@@ -0,0 +1,489 @@
+/*
+ * Single-File-Header for using SPI OLED
+ * 05-05-2023 E. Brombaugh
+ */
+
+#ifndef _SSD1306_H
+#define _SSD1306_H
+
+#include <stdint.h>
+#include <string.h>
+
+// comfortable packet size for this OLED
+#define SSD1306_PSZ 32
+
+// characteristics of each type
+#if !defined(SSD1306_64X32) && !defined(SSD1306_128X32) && !defined(SSD1306_128X64)
+#error "Please define the SSD1306_WXH resolution used in your application"
+#endif
+
+#ifdef SSD1306_64X32
+#define SSD1306_W 64
+#define SSD1306_H 32
+#define SSD1306_FULLUSE
+#define SSD1306_OFFSET 32
+#endif
+
+#ifdef SSD1306_128X32
+#define SSD1306_W 128
+#define SSD1306_H 32
+#define SSD1306_OFFSET 0
+#endif
+
+#ifdef SSD1306_128X64
+#define SSD1306_W 128
+#define SSD1306_H 64
+#define SSD1306_FULLUSE
+#define SSD1306_OFFSET 0
+#endif
+
+/*
+ * send OLED command byte
+ */
+uint8_t ssd1306_cmd(uint8_t cmd)
+{
+	ssd1306_pkt_send(&cmd, 1, 1);
+	return 0;
+}
+
+/*
+ * send OLED data packet (up to 32 bytes)
+ */
+uint8_t ssd1306_data(uint8_t *data, uint8_t sz)
+{
+	ssd1306_pkt_send(data, sz, 0);
+	return 0;
+}
+
+#define SSD1306_SETCONTRAST 0x81
+#define SSD1306_SEGREMAP 0xA0
+#define SSD1306_DISPLAYALLON_RESUME 0xA4
+#define SSD1306_DISPLAYALLON 0xA5
+#define SSD1306_NORMALDISPLAY 0xA6
+#define SSD1306_INVERTDISPLAY 0xA7
+#define SSD1306_DISPLAYOFF 0xAE
+#define SSD1306_DISPLAYON 0xAF
+#define SSD1306_SETDISPLAYOFFSET 0xD3
+#define SSD1306_SETCOMPINS 0xDA
+#define SSD1306_SETVCOMDETECT 0xDB
+#define SSD1306_SETDISPLAYCLOCKDIV 0xD5
+#define SSD1306_SETPRECHARGE 0xD9
+#define SSD1306_SETMULTIPLEX 0xA8
+#define SSD1306_SETLOWCOLUMN 0x00
+#define SSD1306_SETHIGHCOLUMN 0x10
+#define SSD1306_SETSTARTLINE 0x40
+#define SSD1306_MEMORYMODE 0x20
+#define SSD1306_COLUMNADDR 0x21
+#define SSD1306_PAGEADDR 0x22
+#define SSD1306_COMSCANINC 0xC0
+#define SSD1306_COMSCANDEC 0xC8
+#define SSD1306_CHARGEPUMP 0x8D
+#define SSD1306_EXTERNALVCC 0x1
+#define SSD1306_SWITCHCAPVCC 0x2
+#define SSD1306_TERMINATE_CMDS 0xFF
+
+/* choose VCC mode */
+#define SSD1306_EXTERNALVCC 0x1
+#define SSD1306_SWITCHCAPVCC 0x2
+// #define vccstate SSD1306_EXTERNALVCC
+#define vccstate SSD1306_SWITCHCAPVCC
+
+// OLED initialization commands for 128x32
+const uint8_t ssd1306_init_array[] =
+	{
+		SSD1306_DISPLAYOFF,			// 0xAE
+		SSD1306_SETDISPLAYCLOCKDIV, // 0xD5
+		0x80,						// the suggested ratio 0x80
+		SSD1306_SETMULTIPLEX,		// 0xA8
+#ifdef SSD1306_64X32
+		0x1F, // for 64-wide displays
+#else
+		0x3F, // for 128-wide displays
+#endif
+		SSD1306_SETDISPLAYOFFSET,	// 0xD3
+		0x00,						// no offset
+		SSD1306_SETSTARTLINE | 0x0, // 0x40 | line
+		SSD1306_CHARGEPUMP,			// 0x8D
+		0x14,						// enable?
+		SSD1306_MEMORYMODE,			// 0x20
+		0x00,						// 0x0 act like ks0108
+		SSD1306_SEGREMAP | 0x1,		// 0xA0 | bit
+		SSD1306_COMSCANDEC,
+		SSD1306_SETCOMPINS,	 // 0xDA
+		0x12,				 //
+		SSD1306_SETCONTRAST, // 0x81
+		0x8F,
+		SSD1306_SETPRECHARGE, // 0xd9
+		0xF1,
+		SSD1306_SETVCOMDETECT, // 0xDB
+		0x40,
+		SSD1306_DISPLAYALLON_RESUME, // 0xA4
+		SSD1306_NORMALDISPLAY,		 // 0xA6
+		SSD1306_DISPLAYON,			 // 0xAF --turn on oled panel
+		SSD1306_TERMINATE_CMDS		 // 0xFF --fake command to mark end
+};
+
+// the display buffer
+uint8_t ssd1306_buffer[SSD1306_W * SSD1306_H / 8];
+
+/*
+ * set the buffer to a color
+ */
+void ssd1306_setbuf(uint8_t color)
+{
+	memset(ssd1306_buffer, color ? 0xFF : 0x00, sizeof(ssd1306_buffer));
+}
+
+#ifndef SSD1306_FULLUSE
+/*
+ * expansion array for OLED with every other row unused
+ */
+const uint8_t expand[16] =
+	{
+		0x00,
+		0x02,
+		0x08,
+		0x0a,
+		0x20,
+		0x22,
+		0x28,
+		0x2a,
+		0x80,
+		0x82,
+		0x88,
+		0x8a,
+		0xa0,
+		0xa2,
+		0xa8,
+		0xaa,
+};
+#endif
+
+/*
+ * Send the frame buffer
+ */
+void ssd1306_refresh(void)
+{
+	uint16_t i;
+
+	ssd1306_cmd(SSD1306_COLUMNADDR);
+	ssd1306_cmd(SSD1306_OFFSET);				 // Column start address (0 = reset)
+	ssd1306_cmd(SSD1306_OFFSET + SSD1306_W - 1); // Column end address (127 = reset)
+
+	ssd1306_cmd(SSD1306_PAGEADDR);
+	ssd1306_cmd(0); // Page start address (0 = reset)
+	ssd1306_cmd(7); // Page end address
+
+#ifdef SSD1306_FULLUSE
+	/* for fully used rows just plow thru everything */
+	for (i = 0; i < sizeof(ssd1306_buffer); i += SSD1306_PSZ)
+	{
+		/* send PSZ block of data */
+		ssd1306_data(&ssd1306_buffer[i], SSD1306_PSZ);
+	}
+#else
+	/* for displays with odd rows unused expand bytes */
+	uint8_t tbuf[SSD1306_PSZ], j, k;
+	for (i = 0; i < sizeof(ssd1306_buffer); i += 128) // for each page
+	{
+		/* low nybble */
+		for (j = 0; j < 128; j += SSD1306_PSZ)
+		{
+			for (k = 0; k < SSD1306_PSZ; k++)
+				tbuf[k] = expand[ssd1306_buffer[i + j + k] & 0xf];
+
+			/* send PSZ block of data */
+			ssd1306_data(tbuf, SSD1306_PSZ);
+		}
+
+		/* high nybble */
+		for (j = 0; j < 128; j += SSD1306_PSZ)
+		{
+			for (k = 0; k < SSD1306_PSZ; k++)
+				tbuf[k] = expand[(ssd1306_buffer[i + j + k] >> 4) & 0xf];
+
+			/* send PSZ block of data */
+			ssd1306_data(tbuf, SSD1306_PSZ);
+		}
+	}
+#endif
+}
+
+/*
+ * plot a pixel in the buffer
+ */
+void ssd1306_drawPixel(uint8_t x, uint8_t y, uint8_t color)
+{
+	uint16_t addr;
+
+	/* clip */
+	if (x >= SSD1306_W)
+		return;
+	if (y >= SSD1306_H)
+		return;
+
+	/* compute buffer address */
+	addr = x + SSD1306_W * (y / 8);
+
+	/* set/clear bit in buffer */
+	if (color)
+		ssd1306_buffer[addr] |= (1 << (y & 7));
+	else
+		ssd1306_buffer[addr] &= ~(1 << (y & 7));
+}
+
+/*
+ *  fast vert line
+ */
+void ssd1306_drawFastVLine(uint8_t x, uint8_t y, uint8_t h, uint8_t color)
+{
+	// clipping
+	if ((x >= SSD1306_W) || (y >= SSD1306_H))
+		return;
+	if ((y + h - 1) >= SSD1306_H)
+		h = SSD1306_H - y;
+	while (h--)
+	{
+		ssd1306_drawPixel(x, y++, color);
+	}
+}
+
+/*
+ *  fast horiz line
+ */
+void ssd1306_drawFastHLine(uint8_t x, uint8_t y, uint8_t w, uint8_t color)
+{
+	// clipping
+	if ((x >= SSD1306_W) || (y >= SSD1306_H))
+		return;
+	if ((x + w - 1) >= SSD1306_W)
+		w = SSD1306_W - x;
+
+	while (w--)
+	{
+		ssd1306_drawPixel(x++, y, color);
+	}
+}
+
+/*
+ * abs() helper function for line drawing
+ */
+int16_t gfx_abs(int16_t x)
+{
+	return (x < 0) ? -x : x;
+}
+
+/*
+ * swap() helper function for line drawing
+ */
+void gfx_swap(uint16_t *z0, uint16_t *z1)
+{
+	uint16_t temp = *z0;
+	*z0 = *z1;
+	*z1 = temp;
+}
+
+/*
+ * Bresenham line draw routine swiped from Wikipedia
+ */
+void ssd1306_drawLine(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint8_t color)
+{
+	int16_t steep;
+	int16_t deltax, deltay, error, ystep, x, y;
+
+	/* flip sense 45deg to keep error calc in range */
+	steep = (gfx_abs(y1 - y0) > gfx_abs(x1 - x0));
+
+	if (steep)
+	{
+		gfx_swap(&x0, &y0);
+		gfx_swap(&x1, &y1);
+	}
+
+	/* run low->high */
+	if (x0 > x1)
+	{
+		gfx_swap(&x0, &x1);
+		gfx_swap(&y0, &y1);
+	}
+
+	/* set up loop initial conditions */
+	deltax = x1 - x0;
+	deltay = gfx_abs(y1 - y0);
+	error = deltax / 2;
+	y = y0;
+	if (y0 < y1)
+		ystep = 1;
+	else
+		ystep = -1;
+
+	/* loop x */
+	for (x = x0; x <= x1; x++)
+	{
+		/* plot point */
+		if (steep)
+			/* flip point & plot */
+			ssd1306_drawPixel(y, x, color);
+		else
+			/* just plot */
+			ssd1306_drawPixel(x, y, color);
+
+		/* update error */
+		error = error - deltay;
+
+		/* update y */
+		if (error < 0)
+		{
+			y = y + ystep;
+			error = error + deltax;
+		}
+	}
+}
+
+/*
+ *  draws a circle
+ */
+void ssd1306_drawCircle(int16_t x, int16_t y, int16_t radius, int8_t color)
+{
+	/* Bresenham algorithm */
+	int16_t x_pos = -radius;
+	int16_t y_pos = 0;
+	int16_t err = 2 - 2 * radius;
+	int16_t e2;
+
+	do
+	{
+		ssd1306_drawPixel(x - x_pos, y + y_pos, color);
+		ssd1306_drawPixel(x + x_pos, y + y_pos, color);
+		ssd1306_drawPixel(x + x_pos, y - y_pos, color);
+		ssd1306_drawPixel(x - x_pos, y - y_pos, color);
+		e2 = err;
+		if (e2 <= y_pos)
+		{
+			err += ++y_pos * 2 + 1;
+			if (-x_pos == y_pos && e2 <= x_pos)
+			{
+				e2 = 0;
+			}
+		}
+		if (e2 > x_pos)
+		{
+			err += ++x_pos * 2 + 1;
+		}
+	} while (x_pos <= 0);
+}
+
+/*
+ *  draws a filled circle
+ */
+void ssd1306_fillCircle(int16_t x, int16_t y, int16_t radius, int8_t color)
+{
+	/* Bresenham algorithm */
+	int16_t x_pos = -radius;
+	int16_t y_pos = 0;
+	int16_t err = 2 - 2 * radius;
+	int16_t e2;
+
+	do
+	{
+		ssd1306_drawPixel(x - x_pos, y + y_pos, color);
+		ssd1306_drawPixel(x + x_pos, y + y_pos, color);
+		ssd1306_drawPixel(x + x_pos, y - y_pos, color);
+		ssd1306_drawPixel(x - x_pos, y - y_pos, color);
+		ssd1306_drawFastHLine(x + x_pos, y + y_pos, 2 * (-x_pos) + 1, color);
+		ssd1306_drawFastHLine(x + x_pos, y - y_pos, 2 * (-x_pos) + 1, color);
+		e2 = err;
+		if (e2 <= y_pos)
+		{
+			err += ++y_pos * 2 + 1;
+			if (-x_pos == y_pos && e2 <= x_pos)
+			{
+				e2 = 0;
+			}
+		}
+		if (e2 > x_pos)
+		{
+			err += ++x_pos * 2 + 1;
+		}
+	} while (x_pos <= 0);
+}
+
+/*
+ *  draw a rectangle
+ */
+void ssd1306_drawRect(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint8_t color)
+{
+	ssd1306_drawFastVLine(x, y, h, color);
+	ssd1306_drawFastVLine(x + w - 1, y, h, color);
+	ssd1306_drawFastHLine(x, y, w, color);
+	ssd1306_drawFastHLine(x, y + h - 1, w, color);
+}
+
+/*
+ * fill a rectangle
+ */
+void ssd1306_fillRect(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint8_t color)
+{
+	uint8_t m, n = y, iw = w;
+
+	/* scan vertical */
+	while (h--)
+	{
+		m = x;
+		w = iw;
+		/* scan horizontal */
+		while (w--)
+		{
+			/* invert pixels */
+			ssd1306_drawPixel(m++, n, color);
+		}
+		n++;
+	}
+}
+
+/*
+ * invert a rectangle in the buffer
+ */
+void ssd1306_xorrect(uint8_t x, uint8_t y, uint8_t w, uint8_t h)
+{
+	uint8_t m, n = y, iw = w;
+
+	/* scan vertical */
+	while (h--)
+	{
+		m = x;
+		w = iw;
+		/* scan horizontal */
+		while (w--)
+		{
+			/* invert pixels */
+			ssd1306_xorPixel(m++, n);
+		}
+		n++;
+	}
+}
+
+/*
+ * initialize I2C and OLED
+ */
+uint8_t ssd1306_init(void)
+{
+	// pulse reset
+	ssd1306_rst();
+
+	// initialize OLED
+	uint8_t *cmd_list = (uint8_t *)ssd1306_init_array;
+	while (*cmd_list != SSD1306_TERMINATE_CMDS)
+	{
+		if (ssd1306_cmd(*cmd_list++))
+			return 1;
+	}
+
+	// clear display
+	ssd1306_setbuf(0);
+	ssd1306_refresh();
+
+	return 0;
+}
+
+#endif

soweli/ssd1306_i2c.h

@@ -0,0 +1,363 @@
+/*
+ * Single-File-Header for SSD1306 I2C interface
+ * 05-07-2023 E. Brombaugh
+ */
+
+#ifndef _SSD1306_I2C_H
+#define _SSD1306_I2C_H
+
+#include <string.h>
+
+// SSD1306 I2C address
+#define SSD1306_I2C_ADDR 0x3c
+
+// I2C Bus clock rate - must be lower the Logic clock rate
+#define SSD1306_I2C_CLKRATE 1000000
+
+// I2C Logic clock rate - must be higher than Bus clock rate
+#define SSD1306_I2C_PRERATE 2000000
+
+// uncomment this for high-speed 36% duty cycle, otherwise 33%
+#define SSD1306_I2C_DUTY
+
+// I2C Timeout count
+#define TIMEOUT_MAX 100000
+
+// uncomment this to enable IRQ-driven operation
+//#define SSD1306_I2C_IRQ
+
+#ifdef SSD1306_I2C_IRQ
+// some stuff that IRQ mode needs
+volatile uint8_t ssd1306_i2c_send_buffer[64], *ssd1306_i2c_send_ptr, ssd1306_i2c_send_sz, ssd1306_i2c_irq_state;
+
+// uncomment this to enable time diags in IRQ
+//#define IRQ_DIAG
+#endif
+
+/*
+ * init just I2C
+ */
+void ssd1306_i2c_setup(void)
+{
+	uint16_t tempreg;
+	
+	// Reset I2C1 to init all regs
+	RCC->APB1PRSTR |= RCC_APB1Periph_I2C1;
+	RCC->APB1PRSTR &= ~RCC_APB1Periph_I2C1;
+	
+	// set freq
+	tempreg = I2C1->CTLR2;
+	tempreg &= ~I2C_CTLR2_FREQ;
+	tempreg |= (FUNCONF_SYSTEM_CORE_CLOCK/SSD1306_I2C_PRERATE)&I2C_CTLR2_FREQ;
+	I2C1->CTLR2 = tempreg;
+	
+	// Set clock config
+	tempreg = 0;
+#if (SSD1306_I2C_CLKRATE <= 100000)
+	// standard mode good to 100kHz
+	tempreg = (FUNCONF_SYSTEM_CORE_CLOCK/(2*SSD1306_I2C_CLKRATE))&SSD1306_I2C_CKCFGR_CCR;
+#else
+	// fast mode over 100kHz
+#ifndef SSD1306_I2C_DUTY
+	// 33% duty cycle
+	tempreg = (FUNCONF_SYSTEM_CORE_CLOCK/(3*SSD1306_I2C_CLKRATE))&SSD1306_I2C_CKCFGR_CCR;
+#else
+	// 36% duty cycle
+	tempreg = (FUNCONF_SYSTEM_CORE_CLOCK/(25*SSD1306_I2C_CLKRATE))&I2C_CKCFGR_CCR;
+	tempreg |= I2C_CKCFGR_DUTY;
+#endif
+	tempreg |= I2C_CKCFGR_FS;
+#endif
+	I2C1->CKCFGR = tempreg;
+
+#ifdef SSD1306_I2C_IRQ
+	// enable IRQ driven operation
+	NVIC_EnableIRQ(I2C1_EV_IRQn);
+	
+	// initialize the state
+	ssd1306_i2c_irq_state = 0;
+#endif
+	
+	// Enable I2C
+	I2C1->CTLR1 |= I2C_CTLR1_PE;
+
+	// set ACK mode
+	I2C1->CTLR1 |= I2C_CTLR1_ACK;
+}
+
+/*
+ * error descriptions
+ */
+char *errstr[] =
+{
+	"not busy",
+	"master mode",
+	"transmit mode",
+	"tx empty",
+	"transmit complete",
+};
+
+/*
+ * error handler
+ */
+uint8_t ssd1306_i2c_error(uint8_t err)
+{
+	// report error
+	printf("ssd1306_i2c_error - timeout waiting for %s\n\r", errstr[err]);
+	
+	// reset & initialize I2C
+	ssd1306_i2c_setup();
+
+	return 1;
+}
+
+// event codes we use
+#define  SSD1306_I2C_EVENT_MASTER_MODE_SELECT ((uint32_t)0x00030001)  /* BUSY, MSL and SB flag */
+#define  SSD1306_I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED ((uint32_t)0x00070082)  /* BUSY, MSL, ADDR, TXE and TRA flags */
+#define  SSD1306_I2C_EVENT_MASTER_BYTE_TRANSMITTED ((uint32_t)0x00070084)  /* TRA, BUSY, MSL, TXE and BTF flags */
+
+/*
+ * check for 32-bit event codes
+ */
+uint8_t ssd1306_i2c_chk_evt(uint32_t event_mask)
+{
+	/* read order matters here! STAR1 before STAR2!! */
+	uint32_t status = I2C1->STAR1 | (I2C1->STAR2<<16);
+	return (status & event_mask) == event_mask;
+}
+
+#ifdef SSD1306_I2C_IRQ
+/*
+ * packet send for IRQ-driven operation
+ */
+uint8_t ssd1306_i2c_send(uint8_t addr, uint8_t *data, uint8_t sz)
+{
+	int32_t timeout;
+	
+#ifdef IRQ_DIAG
+	GPIOC->BSHR = (1<<(3));
+#endif
+	
+	// error out if buffer under/overflow
+	if((sz > sizeof(ssd1306_i2c_send_buffer)) || !sz)
+		return 2;
+	
+	// wait for previous packet to finish
+	while(ssd1306_i2c_irq_state);
+	
+#ifdef IRQ_DIAG
+	GPIOC->BSHR = (1<<(16+3));
+	GPIOC->BSHR = (1<<(4));
+#endif
+	
+	// init buffer for sending
+	ssd1306_i2c_send_sz = sz;
+	ssd1306_i2c_send_ptr = ssd1306_i2c_send_buffer;
+	memcpy((uint8_t *)ssd1306_i2c_send_buffer, data, sz);
+	
+	// wait for not busy
+	timeout = TIMEOUT_MAX;
+	while((I2C1->STAR2 & I2C_STAR2_BUSY) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(0);
+
+	// Set START condition
+	I2C1->CTLR1 |= I2C_CTLR1_START;
+
+	// wait for master mode select
+	timeout = TIMEOUT_MAX;
+	while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_MODE_SELECT)) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(1);
+	
+	// send 7-bit address + write flag
+	I2C1->DATAR = addr<<1;
+
+	// wait for transmit condition
+	timeout = TIMEOUT_MAX;
+	while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(2);
+
+	// Enable TXE interrupt
+	I2C1->CTLR2 |= I2C_CTLR2_ITBUFEN | I2C_CTLR2_ITEVTEN;
+	ssd1306_i2c_irq_state = 1;
+
+#ifdef IRQ_DIAG
+	GPIOC->BSHR = (1<<(16+4));
+#endif
+	
+	// exit
+	return 0;
+}
+
+/*
+ * IRQ handler for I2C events
+ */
+void I2C1_EV_IRQHandler(void) __attribute__((interrupt));
+void I2C1_EV_IRQHandler(void)
+{
+	uint16_t STAR1, STAR2 __attribute__((unused));
+	
+#ifdef IRQ_DIAG
+	GPIOC->BSHR = (1<<(4));
+#endif
+
+	// read status, clear any events
+	STAR1 = I2C1->STAR1;
+	STAR2 = I2C1->STAR2;
+	
+	/* check for TXE */
+	if(STAR1 & I2C_STAR1_TXE)
+	{
+		/* check for remaining data */
+		if(ssd1306_i2c_send_sz--)
+			I2C1->DATAR = *ssd1306_i2c_send_ptr++;
+
+		/* was that the last byte? */
+		if(!ssd1306_i2c_send_sz)
+		{
+			// disable TXE interrupt
+			I2C1->CTLR2 &= ~(I2C_CTLR2_ITBUFEN | I2C_CTLR2_ITEVTEN);
+			
+			// reset IRQ state
+			ssd1306_i2c_irq_state = 0;
+			
+			// wait for tx complete
+			while(!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_BYTE_TRANSMITTED));
+
+			// set STOP condition
+			I2C1->CTLR1 |= I2C_CTLR1_STOP;
+		}
+	}
+
+#ifdef IRQ_DIAG
+	GPIOC->BSHR = (1<<(16+4));
+#endif
+}
+#else
+/*
+ * low-level packet send for blocking polled operation via i2c
+ */
+uint8_t ssd1306_i2c_send(uint8_t addr, uint8_t *data, uint8_t sz)
+{
+	int32_t timeout;
+	
+	// wait for not busy
+	timeout = TIMEOUT_MAX;
+	while((I2C1->STAR2 & I2C_STAR2_BUSY) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(0);
+
+	// Set START condition
+	I2C1->CTLR1 |= I2C_CTLR1_START;
+	
+	// wait for master mode select
+	timeout = TIMEOUT_MAX;
+	while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_MODE_SELECT)) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(1);
+	
+	// send 7-bit address + write flag
+	I2C1->DATAR = addr<<1;
+
+	// wait for transmit condition
+	timeout = TIMEOUT_MAX;
+	while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(2);
+
+	// send data one byte at a time
+	while(sz--)
+	{
+		// wait for TX Empty
+		timeout = TIMEOUT_MAX;
+		while(!(I2C1->STAR1 & I2C_STAR1_TXE) && (timeout--));
+		if(timeout==-1)
+			return ssd1306_i2c_error(3);
+		
+		// send command
+		I2C1->DATAR = *data++;
+	}
+
+	// wait for tx complete
+	timeout = TIMEOUT_MAX;
+	while((!ssd1306_i2c_chk_evt(SSD1306_I2C_EVENT_MASTER_BYTE_TRANSMITTED)) && (timeout--));
+	if(timeout==-1)
+		return ssd1306_i2c_error(4);
+
+	// set STOP condition
+	I2C1->CTLR1 |= I2C_CTLR1_STOP;
+	
+	// we're happy
+	return 0;
+}
+#endif
+
+/*
+ * high-level packet send for I2C
+ */
+uint8_t ssd1306_pkt_send(uint8_t *data, uint8_t sz, uint8_t cmd)
+{
+	uint8_t pkt[33];
+	
+	/* build command or data packets */
+	if(cmd)
+	{
+		pkt[0] = 0;
+		pkt[1] = *data;
+	}
+	else
+	{
+		pkt[0] = 0x40;
+		memcpy(&pkt[1], data, sz);
+	}
+	return ssd1306_i2c_send(SSD1306_I2C_ADDR, pkt, sz+1);
+}
+
+/*
+ * init I2C and GPIO
+ */
+uint8_t ssd1306_i2c_init(void)
+{
+	// Enable GPIOC and I2C
+	RCC->APB2PCENR |= RCC_APB2Periph_GPIOC;
+	RCC->APB1PCENR |= RCC_APB1Periph_I2C1;
+	
+	// PC1 is SDA, 10MHz Output, alt func, open-drain
+	GPIOC->CFGLR &= ~(0xf<<(4*1));
+	GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_OD_AF)<<(4*1);
+	
+	// PC2 is SCL, 10MHz Output, alt func, open-drain
+	GPIOC->CFGLR &= ~(0xf<<(4*2));
+	GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_OD_AF)<<(4*2);
+	
+#ifdef IRQ_DIAG
+	// GPIO diags on PC3/PC4
+	GPIOC->CFGLR &= ~(0xf<<(4*3));
+	GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*3);
+	GPIOC->BSHR = (1<<(16+3));
+	GPIOC->CFGLR &= ~(0xf<<(4*4));
+	GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP)<<(4*4);
+	GPIOC->BSHR = (1<<(16+4));
+#endif
+
+	// load I2C regs
+	ssd1306_i2c_setup();
+	
+#if 0
+	// test if SSD1306 is on the bus by sending display off command
+	uint8_t command = 0xAF;
+	return ssd1306_pkt_send(&command, 1, 1);
+#else
+	return 0;
+#endif
+}
+
+/*
+ * reset is not used for SSD1306 I2C interface
+ */
+void ssd1306_rst(void)
+{
+}
+#endif