aa9a72b494
This PR does a number of things: 1. Renames the oled_i2c example to sssd1306_i2c to match other example folder names that use the device name 2. Merge code from another ssd1306 exmaple that was sitting in another PR 3. Add a few more demo parts to the code for extra fun. 4. Couple of bug fixes that were reported in original code to fix handling different display sizes, so code now works for 32 and 64 pixel height displays by changing a define at top of code.
440 lines
14 KiB
C
440 lines
14 KiB
C
/**
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* Copyright (c) 2021 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <ctype.h>
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#include "pico/stdlib.h"
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#include "pico/binary_info.h"
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#include "hardware/i2c.h"
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#include "raspberry26x32.h"
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#include "ssd1306_font.h"
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/* Example code to talk to an SSD1306-based OLED display
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The SSD1306 is an OLED/PLED driver chip, capable of driving displays up to
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128x64 pixels.
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NOTE: Ensure the device is capable of being driven at 3.3v NOT 5v. The Pico
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GPIO (and therefore I2C) cannot be used at 5v.
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You will need to use a level shifter on the I2C lines if you want to run the
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board at 5v.
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Connections on Raspberry Pi Pico board, other boards may vary.
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GPIO PICO_DEFAULT_I2C_SDA_PIN (on Pico this is GP4 (pin 6)) -> SDA on display
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board
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GPIO PICO_DEFAULT_I2C_SCL_PIN (on Pico this is GP5 (pin 7)) -> SCL on
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display board
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3.3v (pin 36) -> VCC on display board
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GND (pin 38) -> GND on display board
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*/
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// Define the size of the display we have attached. This can vary, make sure you
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// have the right size defined or the output will look rather odd!
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// Code has been tested on 128x32 and 128x64 OLED displays
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#define SSD1306_HEIGHT 32
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#define SSD1306_WIDTH 128
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#define SSD1306_I2C_ADDR _u(0x3C)
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// 400 is usual, but often these can be overclocked to improve display response.
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// Tested at 1000 on both 32 and 84 pixel height devices and it worked.
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#define SSD1306_I2C_CLK 400
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//#define SSD1306_I2C_CLK 1000
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// commands (see datasheet)
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#define SSD1306_SET_MEM_MODE _u(0x20)
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#define SSD1306_SET_COL_ADDR _u(0x21)
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#define SSD1306_SET_PAGE_ADDR _u(0x22)
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#define SSD1306_SET_HORIZ_SCROLL _u(0x26)
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#define SSD1306_SET_SCROLL _u(0x2E)
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#define SSD1306_SET_DISP_START_LINE _u(0x40)
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#define SSD1306_SET_CONTRAST _u(0x81)
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#define SSD1306_SET_CHARGE_PUMP _u(0x8D)
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#define SSD1306_SET_SEG_REMAP _u(0xA0)
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#define SSD1306_SET_ENTIRE_ON _u(0xA4)
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#define SSD1306_SET_ALL_ON _u(0xA5)
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#define SSD1306_SET_NORM_DISP _u(0xA6)
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#define SSD1306_SET_INV_DISP _u(0xA7)
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#define SSD1306_SET_MUX_RATIO _u(0xA8)
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#define SSD1306_SET_DISP _u(0xAE)
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#define SSD1306_SET_COM_OUT_DIR _u(0xC0)
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#define SSD1306_SET_COM_OUT_DIR_FLIP _u(0xC0)
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#define SSD1306_SET_DISP_OFFSET _u(0xD3)
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#define SSD1306_SET_DISP_CLK_DIV _u(0xD5)
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#define SSD1306_SET_PRECHARGE _u(0xD9)
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#define SSD1306_SET_COM_PIN_CFG _u(0xDA)
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#define SSD1306_SET_VCOM_DESEL _u(0xDB)
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#define SSD1306_PAGE_HEIGHT _u(8)
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#define SSD1306_NUM_PAGES (SSD1306_HEIGHT / SSD1306_PAGE_HEIGHT)
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#define SSD1306_BUF_LEN (SSD1306_NUM_PAGES * SSD1306_WIDTH)
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#define SSD1306_WRITE_MODE _u(0xFE)
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#define SSD1306_READ_MODE _u(0xFF)
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struct render_area {
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uint8_t start_col;
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uint8_t end_col;
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uint8_t start_page;
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uint8_t end_page;
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int buflen;
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};
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void calc_render_area_buflen(struct render_area *area) {
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// calculate how long the flattened buffer will be for a render area
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area->buflen = (area->end_col - area->start_col + 1) * (area->end_page - area->start_page + 1);
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}
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#ifdef i2c_default
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inline void SSD1306_send_cmd(uint8_t cmd) {
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// I2C write process expects a control byte followed by data
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// this "data" can be a command or data to follow up a command
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// Co = 1, D/C = 0 => the driver expects a command
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uint8_t buf[2] = {0x80, cmd};
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i2c_write_blocking(i2c_default, (SSD1306_I2C_ADDR & SSD1306_WRITE_MODE), buf, 2, false);
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}
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void SSD1306_send_cmd_list(uint8_t *buf, int num) {
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for (int i=0;i<num;i++)
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SSD1306_send_cmd(buf[i]);
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}
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void SSD1306_send_buf(uint8_t buf[], int buflen) {
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// in horizontal addressing mode, the column address pointer auto-increments
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// and then wraps around to the next page, so we can send the entire frame
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// buffer in one gooooooo!
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// copy our frame buffer into a new buffer because we need to add the control byte
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// to the beginning
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uint8_t *temp_buf = malloc(buflen + 1);
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temp_buf[0] = 0x40;
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memcpy(temp_buf+1, buf, buflen);
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i2c_write_blocking(i2c_default, (SSD1306_I2C_ADDR & SSD1306_WRITE_MODE), temp_buf, buflen + 1, false);
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free(temp_buf);
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}
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void SSD1306_init() {
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// Some of these commands are not strictly necessary as the reset
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// process defaults to some of these but they are shown here
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// to demonstrate what the initialization sequence looks like
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// Some configuration values are recommended by the board manufacturer
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uint8_t cmds[] = {
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SSD1306_SET_DISP, // set display off
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/* memory mapping */
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SSD1306_SET_MEM_MODE, // set memory address mode 0 = horizontal, 1 = vertical, 2 = page
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0x00, // horizontal addressing mode
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/* resolution and layout */
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SSD1306_SET_DISP_START_LINE, // set display start line to 0
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SSD1306_SET_SEG_REMAP | 0x01, // set segment re-map, column address 127 is mapped to SEG0
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SSD1306_SET_MUX_RATIO, // set multiplex ratio
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SSD1306_HEIGHT - 1, // Display height - 1
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SSD1306_SET_COM_OUT_DIR | 0x08, // set COM (common) output scan direction. Scan from bottom up, COM[N-1] to COM0
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SSD1306_SET_DISP_OFFSET, // set display offset
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0x00, // no offset
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SSD1306_SET_COM_PIN_CFG, // set COM (common) pins hardware configuration. Board specific magic number.
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// 0x02 Works for 128x32, 0x12 Possibly works for 128x64. Other options 0x22, 0x32
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#if ((SSD1306_WIDTH == 128) && (SSD1306_HEIGHT == 32))
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0x02,
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#elif ((SSD1306_WIDTH == 128) && (SSD1306_HEIGHT == 64))
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0x12,
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#else
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0x02,
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#endif
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/* timing and driving scheme */
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SSD1306_SET_DISP_CLK_DIV, // set display clock divide ratio
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0x80, // div ratio of 1, standard freq
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SSD1306_SET_PRECHARGE, // set pre-charge period
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0xF1, // Vcc internally generated on our board
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SSD1306_SET_VCOM_DESEL, // set VCOMH deselect level
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0x30, // 0.83xVcc
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/* display */
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SSD1306_SET_CONTRAST, // set contrast control
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0xFF,
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SSD1306_SET_ENTIRE_ON, // set entire display on to follow RAM content
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SSD1306_SET_NORM_DISP, // set normal (not inverted) display
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SSD1306_SET_CHARGE_PUMP, // set charge pump
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0x14, // Vcc internally generated on our board
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SSD1306_SET_SCROLL | 0x00, // deactivate horizontal scrolling if set. This is necessary as memory writes will corrupt if scrolling was enabled
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SSD1306_SET_DISP | 0x01, // turn display on
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};
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SSD1306_send_cmd_list(cmds, count_of(cmds));
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}
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void SSD1306_scroll(bool on) {
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// configure horizontal scrolling
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uint8_t cmds[] = {
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SSD1306_SET_HORIZ_SCROLL | 0x00,
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0x00, // dummy byte
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0x00, // start page 0
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0x00, // time interval
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0x03, // end page 3 SSD1306_NUM_PAGES ??
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0x00, // dummy byte
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0xFF, // dummy byte
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SSD1306_SET_SCROLL | (on ? 0x01 : 0) // Start/stop scrolling
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};
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SSD1306_send_cmd_list(cmds, count_of(cmds));
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}
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void render(uint8_t *buf, struct render_area *area) {
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// update a portion of the display with a render area
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uint8_t cmds[] = {
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SSD1306_SET_COL_ADDR,
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area->start_col,
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area->end_col,
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SSD1306_SET_PAGE_ADDR,
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area->start_page,
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area->end_page
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};
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SSD1306_send_cmd_list(cmds, count_of(cmds));
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SSD1306_send_buf(buf, area->buflen);
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}
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static void SetPixel(uint8_t *buf, int x,int y, bool on) {
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assert(x >= 0 && x < SSD1306_WIDTH && y >=0 && y < SSD1306_HEIGHT);
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// The calculation to determine the correct bit to set depends on which address
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// mode we are in. This code assumes horizontal
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// The video ram on the SSD1306 is split up in to 8 rows, one bit per pixel.
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// Each row is 128 long by 8 pixels high, each byte vertically arranged, so byte 0 is x=0, y=0->7,
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// byte 1 is x = 1, y=0->7 etc
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// This code could be optimised, but is like this for clarity. The compiler
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// should do a half decent job optimising it anyway.
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const int BytesPerRow = SSD1306_WIDTH ; // x pixels, 1bpp, but each row is 8 pixel high, so (x / 8) * 8
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int byte_idx = (y / 8) * BytesPerRow + x;
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uint8_t byte = buf[byte_idx];
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if (on)
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byte |= 1 << (y % 8);
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else
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byte &= ~(1 << (y % 8));
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buf[byte_idx] = byte;
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}
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// Basic Bresenhams.
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static void DrawLine(uint8_t *buf, int x0, int y0, int x1, int y1, bool on) {
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int dx = abs(x1-x0);
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int sx = x0<x1 ? 1 : -1;
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int dy = -abs(y1-y0);
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int sy = y0<y1 ? 1 : -1;
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int err = dx+dy;
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int e2;
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while (true) {
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SetPixel(buf, x0, y0, on);
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if (x0 == x1 && y0 == y1)
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break;
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e2 = 2*err;
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if (e2 >= dy) {
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err += dy;
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x0 += sx;
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}
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if (e2 <= dx) {
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err += dx;
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y0 += sy;
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}
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}
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}
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static inline int GetFontIndex(uint8_t ch) {
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if (ch >= 'A' && ch <='Z') {
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return ch - 'A' + 1;
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}
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else if (ch >= '0' && ch <='9') {
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return ch - '0' + 27;
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}
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else return 0; // Not got that char so space.
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}
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static uint8_t reversed[sizeof(font)] = {0};
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static uint8_t reverse(uint8_t b) {
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b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
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b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
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b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
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return b;
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}
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static void FillReversedCache() {
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// calculate and cache a reversed version of fhe font, because I defined it upside down...doh!
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for (int i=0;i<sizeof(font);i++)
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reversed[i] = reverse(font[i]);
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}
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static void WriteChar(uint8_t *buf, int16_t x, int16_t y, uint8_t ch) {
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if (reversed[0] == 0)
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FillReversedCache();
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if (x > SSD1306_WIDTH - 8 || y > SSD1306_HEIGHT - 8)
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return;
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// For the moment, only write on Y row boundaries (every 8 vertical pixels)
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y = y/8;
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ch = toupper(ch);
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int idx = GetFontIndex(ch);
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int fb_idx = y * 128 + x;
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for (int i=0;i<8;i++) {
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buf[fb_idx++] = reversed[idx * 8 + i];
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}
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}
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static void WriteString(uint8_t *buf, int16_t x, int16_t y, char *str) {
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// Cull out any string off the screen
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if (x > SSD1306_WIDTH - 8 || y > SSD1306_HEIGHT - 8)
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return;
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while (*str) {
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WriteChar(buf, x, y, *str++);
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x+=8;
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}
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}
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#endif
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int main() {
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stdio_init_all();
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#if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN)
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#warning i2c / SSD1306_i2d example requires a board with I2C pins
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puts("Default I2C pins were not defined");
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#else
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// useful information for picotool
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bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C));
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bi_decl(bi_program_description("SSD1306 OLED driver I2C example for the Raspberry Pi Pico"));
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printf("Hello, SSD1306 OLED display! Look at my raspberries..\n");
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// I2C is "open drain", pull ups to keep signal high when no data is being
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// sent
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i2c_init(i2c_default, SSD1306_I2C_CLK * 1000);
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gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
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gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
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gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
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gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
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// run through the complete initialization process
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SSD1306_init();
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// Initialize render area for entire frame (SSD1306_WIDTH pixels by SSD1306_NUM_PAGES pages)
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struct render_area frame_area = {
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start_col: 0,
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end_col : SSD1306_WIDTH - 1,
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start_page : 0,
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end_page : SSD1306_NUM_PAGES - 1
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};
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calc_render_area_buflen(&frame_area);
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// zero the entire display
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uint8_t buf[SSD1306_BUF_LEN];
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memset(buf, 0, SSD1306_BUF_LEN);
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render(buf, &frame_area);
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// intro sequence: flash the screen 3 times
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for (int i = 0; i < 3; i++) {
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SSD1306_send_cmd(SSD1306_SET_ALL_ON); // Set all pixels on
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sleep_ms(500);
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SSD1306_send_cmd(SSD1306_SET_ENTIRE_ON); // go back to following RAM for pixel state
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sleep_ms(500);
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}
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// render 3 cute little raspberries
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struct render_area area = {
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start_page : 0,
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end_page : (IMG_HEIGHT / SSD1306_PAGE_HEIGHT) - 1
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};
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restart:
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area.start_col = 0;
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area.end_col = IMG_WIDTH - 1;
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calc_render_area_buflen(&area);
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uint8_t offset = 5 + IMG_WIDTH; // 5px padding
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for (int i = 0; i < 3; i++) {
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render(raspberry26x32, &area);
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area.start_col += offset;
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area.end_col += offset;
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}
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SSD1306_scroll(true);
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sleep_ms(5000);
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SSD1306_scroll(false);
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char *text[] = {
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"A long time ago",
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" on an OLED ",
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" display",
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" far far away",
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"Lived a small",
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"red raspberry",
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"by the name of",
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" PICO"
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};
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int y = 0;
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for (int i = 0 ;i < count_of(text); i++) {
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WriteString(buf, 5, y, text[i]);
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y+=8;
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}
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render(buf, &frame_area);
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// Test the display invert function
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sleep_ms(3000);
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SSD1306_send_cmd(SSD1306_SET_INV_DISP);
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sleep_ms(3000);
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SSD1306_send_cmd(SSD1306_SET_NORM_DISP);
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bool pix = true;
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for (int i = 0; i < 2;i++) {
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for (int x = 0;x < SSD1306_WIDTH;x++) {
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DrawLine(buf, x, 0, SSD1306_WIDTH - 1 - x, SSD1306_HEIGHT - 1, pix);
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render(buf, &frame_area);
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}
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for (int y = SSD1306_HEIGHT-1; y >= 0 ;y--) {
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DrawLine(buf, 0, y, SSD1306_WIDTH - 1, SSD1306_HEIGHT - 1 - y, pix);
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render(buf, &frame_area);
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}
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pix = false;
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}
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goto restart;
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#endif
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return 0;
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}
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