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Lecture fb
commit d004e5324173f4fb0befa471fb53df1090e0cb33 Author: Julie Zelenski <[email protected]> Date: Mon Nov 4 10:01:42 2024 -0800 Lecture fb
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14 files changed

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-3
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14 files changed

+324
-3
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‎_data/unreleased.csv‎

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@@ -6,7 +6,6 @@ permalink,title,released
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"/labs/projectlab1/","Lab 8: Project Team Meeting 1",false
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"/labs/projectlab2/","Lab 9: Project Team Meeting 2",false
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"/lectures/FloatingPoint_Sound/","Floating Point and Sound",false
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"/lectures/Framebuffer/","Graphics and the framebuffer",false
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"/lectures/Guest/","Guest",false
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"/lectures/InfoSession/","Course Info Session",false
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"/lectures/Interrupts1/","Interrupts",false

‎lectures/Arithmetic/code/integers/main.c‎

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#include <stdint.h>
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#include "printf.h"
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#include "uart.h"
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#include "timer.h"
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void bug_compare(void) {
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int a = -20;
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unsigned int b = 6;
@@ -12,6 +12,30 @@ void bug_compare(void) {
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printf("-20 >= 6 - omg \n");
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}
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unsigned int get_count() {
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static unsigned int count = 0xfffff000;
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return ++count;
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}
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void delay_ticks(unsigned int us) {
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unsigned int enough = us * 24;
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unsigned int start = get_count();
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unsigned int sofar = 0;
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unsigned int stop_at = start + enough;
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unsigned int now = 0;
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int count = 0;
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//while (get_count() - start < enough) {
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while (get_count() < start + enough) {
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count++;
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//now = get_count();
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//sofar = now - start;
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//if (get_count() - start >= enough) break;
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//if (now >= stop_at) break;
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}
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printf("iterated %d times, start was %02x, delta enough %d delta sofar %d stopat %x now %x\n", count, start, enough, sofar, stop_at, now);
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}
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void overflow(void) {
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for (unsigned char i = 0; i < 256; i++)
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printf("0x%2x\n", i);
@@ -41,5 +65,8 @@ void main(void) {
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// overflow();
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// bug_compare();
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conversions();
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// conversions();
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for (int i = 0; i < 50; i++) {
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delay_ticks(5);
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}
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}

‎lectures/Framebuffer/README.md‎

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---
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released: true
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permalink: /lectures/Framebuffer/
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title: Graphics and the framebuffer
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readings: |
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+ [cdecl](https://cdecl.org) for unraveling C types
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+ Documentation for Mango Pi [Display Engine](readings/Allwinner_DE2.0_Spec_V1.0.pdf)
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+ [HDMI spec](https://hdmi.org/spec/index)
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---

‎lectures/Framebuffer/code/clear/Makefile‎

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NAME = clear
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ARCH = -march=rv64im -mabi=lp64
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ASFLAGS = $(ARCH)
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CFLAGS = $(ARCH) -g -Og -I$$CS107E/include -Wall -ffreestanding
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LDFLAGS = -nostdlib -L$$CS107E/lib -T memmap.ld
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LDLIBS = -lmango -lmango_gcc
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all : $(NAME).bin
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%.bin: %.elf
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riscv64-unknown-elf-objcopy $< -O binary $@
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%.elf: %.o
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riscv64-unknown-elf-gcc $(LDFLAGS) $^ $(LDLIBS) -o $@
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%.o: %.c
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riscv64-unknown-elf-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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riscv64-unknown-elf-as $(ASFLAGS) $< -o $@
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run: $(NAME).bin
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mango-run $<
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clean:
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rm -f *.o *.bin *.elf *.list *~
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.PHONY: all clean run
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.PRECIOUS: %.elf %.o

‎lectures/Framebuffer/code/clear/README.md‎

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Show how to clear the framebuffer memory accessing using different array layout
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- `clear_char_by_char`: access as 1D array of unsigned char's
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- `clear_int_by_int`: access a 1D array of unsigned int's
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- `clear_2d`: access a 2D array of unsigned int's

‎lectures/Framebuffer/code/clear/clear.c‎

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#include "fb.h"
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#include "de.h"
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#include "hdmi.h"
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#include "malloc.h"
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#include "printf.h"
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#include "uart.h"
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// module-level variables
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static struct {
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int width; // count of horizontal pixels
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int height; // count of vertical pixels
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int depth; // num bytes per pixel
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void *framebuffer; // address of framebuffer memory
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} module;
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void fb_init(int width, int height, fb_mode_t mode) {
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module.width = width;
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module.height = height;
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module.depth = 4; // our pixels always 32-bit
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int nbytes = module.width * module.height * module.depth;
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module.framebuffer = malloc(nbytes);
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// what will be contents of newly malloc'ed memory block?
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hdmi_resolution_id_t id = hdmi_best_match(width, height); // choose from available screen resolutions
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hdmi_init(id);
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de_init(width, height, hdmi_get_screen_width(), hdmi_get_screen_height());
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de_set_active_framebuffer(module.framebuffer);
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}
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static void clear_char_by_char(void) {
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uint8_t *im = module.framebuffer;
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int total_bytes = module.width * module.height * module.depth;
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// write each byte in the framebuffer
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for (int i = 0; i < total_bytes; i++) {
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*im++ = 0xff; // white
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}
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}
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static void clear_int_by_int_green(void) {
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unsigned int *im = module.framebuffer;
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int npixels = module.width * module.height;
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for (int i = 0; i < npixels; i++) {
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*im++ = 0xff00ff00; // green
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}
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}
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static void clear_2d_purple(void) {
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unsigned int (*im)[module.width] = module.framebuffer;
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for (int y = 0; y < module.height; y++) {
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for (int x = 0; x < module.width; x++) {
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im[y][x] = 0xffff00ff; // purple
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}
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}
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}
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static bool confirm(const char *msg) {
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printf("Next: %s. Hit any key when ready (q to quit): ", msg);
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int ch = uart_getchar();
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printf("%c\n", ch);
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return ch != 'q';
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}
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void main(void) {
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uart_init();
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fb_init(1600, 900, FB_SINGLEBUFFER);
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printf("Screen size %d x %d\n", hdmi_get_screen_width(), hdmi_get_screen_height());
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printf("Framebuffer size %d x %d\n", module.width, module.height);
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clear_char_by_char();
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while (1) {
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if (!confirm("clear to white, char by char")) break;
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clear_char_by_char();
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if (!confirm("clear to green, int by int")) break;
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clear_int_by_int_green();
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if (!confirm("clear to purple, 2-D of int")) break;
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clear_2d_purple();
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}
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printf("Completed %s\n", __FILE__);
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}

‎lectures/Framebuffer/code/console/Makefile‎

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NAME = joshua
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ARCH = -march=rv64im -mabi=lp64
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ASFLAGS = $(ARCH)
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CFLAGS = $(ARCH) -g -Og -I$$CS107E/include -Wall -ffreestanding
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LDFLAGS = -nostdlib -L$$CS107E/lib -T memmap.ld
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LDLIBS = -lmango -lmango_gcc
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all : $(NAME).bin
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%.bin: %.elf
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riscv64-unknown-elf-objcopy $< -O binary $@
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%.elf: %.o
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riscv64-unknown-elf-gcc $(LDFLAGS) $^ $(LDLIBS) -o $@
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%.o: %.c
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riscv64-unknown-elf-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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riscv64-unknown-elf-as $(ASFLAGS) $< -o $@
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run: $(NAME).bin
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mango-run $<
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clean:
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rm -f *.o *.bin *.elf *.list *~
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.PHONY: all clean run
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.PRECIOUS: %.elf %.o

‎lectures/Framebuffer/code/console/joshua.c‎

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#include "console.h"
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#include "timer.h"
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void main(void)
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{
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console_init(20, 32, GL_AMBER, GL_BLACK);
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console_printf("GREETINGS PROFESSOR FALKEN\n");
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console_printf("\n");
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timer_delay_ms(2000);
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console_printf("HELLO\n");
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console_printf("\n");
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timer_delay_ms(2000);
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console_printf("A STRANGE GAME\n");
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timer_delay_ms(2000);
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console_printf("THE ONLY WINNING MOVE IS\n");
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timer_delay_ms(2000);
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console_printf("NOT TO PLAY\n");
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console_printf("\n");
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timer_delay_ms(2000);
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console_printf("HOW ABOUT A NICE GAME OF CHESS?\n");
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timer_delay_ms(2000);
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}
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‎lectures/Framebuffer/code/doublebuffer/Makefile‎

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NAME = hello
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ARCH = -march=rv64im -mabi=lp64
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ASFLAGS = $(ARCH)
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CFLAGS = $(ARCH) -g -Og -I$$CS107E/include -Wall -ffreestanding
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LDFLAGS = -nostdlib -L$$CS107E/lib -T memmap.ld
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LDLIBS = -lmango -lmango_gcc
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all : $(NAME).bin
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%.bin: %.elf
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riscv64-unknown-elf-objcopy $< -O binary $@
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%.elf: %.o
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riscv64-unknown-elf-gcc $(LDFLAGS) $^ $(LDLIBS) -o $@
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%.o: %.c
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riscv64-unknown-elf-gcc $(CFLAGS) -c $< -o $@
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%.o: %.s
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riscv64-unknown-elf-as $(ASFLAGS) $< -o $@
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run: $(NAME).bin
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mango-run $<
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clean:
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rm -f *.o *.bin *.elf *.list *~
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.PHONY: all clean run
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.PRECIOUS: %.elf %.o

‎lectures/Framebuffer/code/doublebuffer/README.md‎

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When in single buffer mode, repeatedly clear and print string will produce
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a lot of jitter/tearing
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Change to double buffer mode and there is smooth transition from
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one frame to another, neat!

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