Have getc, halting, timer, graphics, mode switching

.gitignore

@@ -15,3 +15,4 @@ cmake-build-debug
 CMakeLists.txt
 __pycache__
 res.txt
+vibing.txt

Makefile

@@ -106,7 +106,7 @@ debug-nox: image.bin
 		-ex "break _start" \
 		-ex "continue"
 
-USERPROGS=./user/false ./user/greet ./user/div0 ./user/shout ./user/badputs ./user/bss
+USERPROGS=./user/false ./user/greet ./user/div0 ./user/shout ./user/badputs ./user/bss ./user/snake
 
 fs.img: ./kernel.bin ./tools/mkfs $(USERPROGS)
 	./tools/mkfs $@ $< $(USERPROGS)

cpu/idt.c

@@ -3,7 +3,10 @@
 #include "memlayout.h"
 #include "../syscall.h"
 #include "../proc.h"
+#include "../drivers/keyboard.h"
 #include "../drivers/port.h"
+#include "../drivers/pit.h"
+#include "../drivers/vga.h"
 #include "../console.h"
 
 enum {
@@ -147,7 +150,31 @@ bool is_userspace_ptr_mapped(uint32_t ptr) {
     return 1;
 }
 
-static void* get_userspace_cstr(uint32_t ptr) {
+static bool is_userspace_range_mapped(uint32_t ptr, uint32_t size) {
+    if (size == 0) {
+        return 1;
+    }
+    if (ptr >= KERNBASE) {
+        return 0;
+    }
+
+    uint32_t end = ptr + size - 1;
+    if (end < ptr || end >= KERNBASE) {
+        return 0;
+    }
+
+    uint32_t last_page = PGROUNDDOWN(end);
+    for (uint32_t addr = ptr;; addr = PGROUNDDOWN(addr) + PGSIZE) {
+        if (!is_userspace_ptr_mapped(addr)) {
+            return 0;
+        }
+        if (PGROUNDDOWN(addr) == last_page) {
+            return 1;
+        }
+    }
+}
+
+static bool is_userspace_cstr(uint32_t ptr) {
     for (uint32_t addr = ptr;; addr++) {
         if (addr == 0 || !is_userspace_ptr_mapped(addr)) {
             return 0;
@@ -158,16 +185,75 @@ static void* get_userspace_cstr(uint32_t ptr) {
     }
 }
 
-static int handle_puts(const char* s) {
-    if (!s) {
+static _Noreturn void userspace_panic(const char* msg) {
+    if (!vga_is_text_mode()) {
+        switch_to_text_mode();
+        vga_clear_screen();
+    }
+    printk(msg);
+    killproc();
+}
+
+static void handle_puts(uintptr_t s) {
+    if (!is_userspace_cstr(s)) {
+        userspace_panic("SYS_puts panic: page fault\n");
+    }
+    printk((const char*)s);
+}
+
+static void require_text_mode_for_userspace_text_syscall() {
+    if (!vga_is_text_mode()) {
+        userspace_panic("Userspace panic: text syscall in graphics mode\n");
+    }
+}
+
+static void handle_swap_frame(uintptr_t frame) {
+    enum {
+        VGA_GRAPHICS_FRAME_SIZE = VGA_GRAPHICS_WIDTH * VGA_GRAPHICS_HEIGHT,
+    };
+
+    if (vga_is_text_mode()) {
+        userspace_panic("Userspace panic: frame swap in text mode\n");
+    }
+    if (!is_userspace_range_mapped(frame, VGA_GRAPHICS_FRAME_SIZE)) {
+        userspace_panic("SYS_swap_frame panic: page fault\n");
+    }
+
+    uint8_t *video = (uint8_t*)(KERNBASE + 0xA0000);
+    uint8_t *user = (uint8_t*)frame;
+    for (uint32_t i = 0; i < VGA_GRAPHICS_FRAME_SIZE; i++) {
+        video[i] = user[i];
+    }
+}
+
+static void refill_keyboard_copy_buffer(void) {
+    size_t count = kbd_state_shrd.len;
+    if (count == 0) {
+        return;
+    }
+
+    cli();
+    size_t rem = KEYBOARD_INTERRUPT_BUF_CAP - kbd_state_shrd.copy_len;
+    size_t copying = rem < count ? rem : count;
+    memcpy(kbd_state_shrd.copy_buf, kbd_state_shrd.buf, copying);
+    kbd_state_shrd.len -= copying;
+    kbd_state_shrd.copy_len += copying;
+    sti();
+}
+
+static int handle_getc(void) {
+    if (kbd_can_take_from_copy_buffer()) {
+        return kbd_take_from_copy_buffer();
+    }
+
+    refill_keyboard_copy_buffer();
+    if (!kbd_can_take_from_copy_buffer()) {
         return -1;
     }
-    printk(s);
-    return 0;
+    return kbd_take_from_copy_buffer();
 }
 
 static void handle_syscall(registers_t* r) {
-    int ret;
     switch (r->eax) {
         case SYS_exit:
             if (r->ebx == 0) {
@@ -177,24 +263,44 @@ static void handle_syscall(registers_t* r) {
             }
             killproc();
         case SYS_greet:
+            require_text_mode_for_userspace_text_syscall();
             printk("Hello world!\n");
             r->eax = 0;
             break;
         case SYS_putc:
-            printk((const char[]){r->ebx, '\0'});
+            require_text_mode_for_userspace_text_syscall();
+            printk((const char[]){(char)r->ebx, '\0'});
             r->eax = 0;
             break;
         case SYS_puts:
-            ret = handle_puts(get_userspace_cstr(r->ebx));
-            if (ret < 0) {
-                printk("SYS_puts panic: page fault\n");
-                killproc();
-            }
+            require_text_mode_for_userspace_text_syscall();
+            handle_puts(r->ebx);
             r->eax = 0;
             break;
+        case SYS_switch_to_text:
+            switch_to_text_mode();
+            r->eax = 0;
+            break;
+        case SYS_switch_to_graphics:
+            switch_to_graphics_mode();
+            r->eax = 0;
+            break;
+        case SYS_swap_frame:
+            handle_swap_frame(r->ebx);
+            r->eax = 0;
+            break;
+        case SYS_time_ms:
+            r->eax = get_uptime_ms();
+            break;
+        case SYS_halt:
+            asm volatile("hlt");
+            r->eax = 0;
+            break;
+        case SYS_getc:
+            r->eax = handle_getc();
+            break;
         default:
-            printk("Userspace panic: Unknown syscall\n");
-            killproc();
+            userspace_panic("Userspace panic: Unknown syscall\n");
     }
 }
 

drivers/graphics.c

@@ -4,10 +4,13 @@
    borrowed bits from http://files.osdev.org/mirrors/geezer/osd/graphics/modes.c 
 
 */
+#include "vga.h"
 #include "cpu/x86.h"
 #include "cpu/memlayout.h"
 #include "port.h"
 
+static vga_display_mode_t current_display_mode = VGA_DISPLAY_MODE_TEXT;
+
 static inline char inb(int port) {
 	return port_byte_in(port);
 }
@@ -410,6 +413,7 @@ void vgaMode13() {
       outb(0x3C0, 0x20);
 
       setdefaultVGApalette();
+      current_display_mode = VGA_DISPLAY_MODE_GRAPHICS;
 }
 
 void vgaMode3() {
@@ -518,4 +522,21 @@ void vgaMode3() {
 
       inb(VGA+0x1A);
       outb(0x3C0, 0x20);
+      current_display_mode = VGA_DISPLAY_MODE_TEXT;
+}
+
+void switch_to_graphics_mode() {
+  vgaMode13();
+}
+
+void switch_to_text_mode() {
+  vgaMode3();
+}
+
+vga_display_mode_t vga_get_display_mode() {
+  return current_display_mode;
+}
+
+bool vga_is_text_mode() {
+  return current_display_mode == VGA_DISPLAY_MODE_TEXT;
 }

drivers/pit.c

@@ -25,8 +25,11 @@ enum {
     PIT_MODES_HW_TRIGGERRED_STROBE = 0x5,
 };
 
+
+// Wtf is that O_o
 static timer_callback callbacks[100];
 static int registered_callbacks = 0;
+static volatile uint32_t uptime_ms = 0;
 
 void add_timer_callback(timer_callback tc) {
     callbacks[registered_callbacks++] = tc;
@@ -45,7 +48,7 @@ struct pit_command_t {
     unsigned char select_channel : 2;
 } __attribute__((packed));
 
-static void dec_sleep_counter(void);
+static void timer_int_callback(void);
 
 void init_pit() {
     struct pit_command_t cmd = {
@@ -59,15 +62,20 @@ void init_pit() {
     port_byte_out(0x40, (PIT_PROGRAM_REG & 0xff00) >> 8);
 
     register_interrupt_handler(IRQ0, timer_interrupt_handler);
-    add_timer_callback(dec_sleep_counter);
+    add_timer_callback(timer_int_callback);
 }
 
 static volatile int sleep_counter = 0;
 
-static void dec_sleep_counter(void) {
+static void timer_int_callback(void) {
+    uptime_ms += 1000 / CLOCK_PRECISION_HZ;
     sleep_counter--;
 }
 
+uint32_t get_uptime_ms(void) {
+    return uptime_ms;
+}
+
 void msleep(int ms) {
     sleep_counter = ms / 10;
     while (sleep_counter > 0) {

drivers/pit.h

@@ -1,8 +1,11 @@
 #pragma once
 
+#include <stdint.h>
+
 typedef void (*timer_callback)(void);
 
 void init_pit(void);
 void add_timer_callback(timer_callback tc);
 
+uint32_t get_uptime_ms(void);
 void msleep(int ms);

drivers/vga.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <stdbool.h>
 #include <stdint.h>
 
 enum {
@@ -23,5 +24,17 @@ void vga_clear_screen();
 void vga_set_char(unsigned offset, char c);
 void vga_print_string(const char* s);
 
+#define VGA_GRAPHICS_WIDTH 320
+#define VGA_GRAPHICS_HEIGHT 200
+
+typedef enum {
+  VGA_DISPLAY_MODE_TEXT = 0,
+  VGA_DISPLAY_MODE_GRAPHICS = 1,
+} vga_display_mode_t;
+
 void vgaMode13();
 void vgaMode3();
+void switch_to_graphics_mode();
+void switch_to_text_mode();
+vga_display_mode_t vga_get_display_mode();
+bool vga_is_text_mode();

kernel.c

@@ -19,14 +19,14 @@ void vga_set_pixel(int x, int y, int color) {
 }
 
 void graphtest() {
-    vgaMode13();
+    switch_to_graphics_mode();
     for (int i = 0; i < 320; ++i) {
         for (int j = 0; j < 200; ++j) {
             vga_set_pixel(i, j, (i+j)/2);
         }
     }
     msleep(5000);
-    vgaMode3();
+    switch_to_text_mode();
     vga_clear_screen();
 }
 

proc.c

@@ -1,4 +1,5 @@
 #include "proc.h"
+#include "drivers/vga.h"
 
 struct context {
     // matches the behavior of swtch()
@@ -28,9 +29,9 @@ void trapret();
 void swtch(void** oldstack, void* newstack);
 
 pde_t *get_user_proc_page_directory() {
-    // if (!vm.user_task) {
-    //     return 0;
-    // }
+    if (!vm.user_task) {
+        return 0;
+    }
     return vm.user_task->pgdir;
 }
 
@@ -87,6 +88,10 @@ void run_elf(const char* name) {
 
 _Noreturn void killproc() {
     void* task_stack;
+    if (!vga_is_text_mode()) {
+        switch_to_text_mode();
+        vga_clear_screen();
+    }
     switchkvm();
     freevm(vm.user_task->pgdir);
     sti();

syscall.h

@@ -8,6 +8,12 @@ enum {
 	SYS_greet = 1,
 	SYS_putc = 2,
 	SYS_puts = 3,
+	SYS_switch_to_text = 4,
+	SYS_switch_to_graphics = 5,
+	SYS_swap_frame = 6,
+	SYS_time_ms = 7,
+	SYS_halt = 8,
+	SYS_getc = 9,
 };
 
 int syscall(int call, uintptr_t arg);

user/snake.c

@@ -1,8 +1,61 @@
 #include "../syscall.h"
+#include "../drivers/vga.h"
 #include <stdint.h>
-#include <stdbool.h>
 
-int main() {
-    return 0;
+enum {
+    FRAME_SIZE = VGA_GRAPHICS_WIDTH * VGA_GRAPHICS_HEIGHT,
+    BLOCK_WIDTH = 270,
+    BLOCK_HEIGHT = 100,
+    BLOCK_X = 10,
+    BLOCK_Y = 0,
+};
 
+// Non-zero initializer keeps the framebuffer in the program image, which this
+// loader maps more reliably than a large BSS object.
+static uint8_t frame[FRAME_SIZE] = { 1 };
+
+static uint32_t time_ms(void) {
+    return (uint32_t)syscall(SYS_time_ms, 0);
+}
+
+static void clear_frame(uint8_t color) {
+    for (uint32_t i = 0; i < FRAME_SIZE; i++) {
+        frame[i] = color;
+    }
+}
+
+static void put_pixel(int x, int y, uint8_t color) {
+    if (x < 0 || x >= VGA_GRAPHICS_WIDTH || y < 0 || y >= VGA_GRAPHICS_HEIGHT) {
+        return;
+    }
+    frame[y * VGA_GRAPHICS_WIDTH + x] = color;
+}
+
+static void draw_demo(void) {
+    clear_frame(0x01);
+
+    for (int y = 0; y < BLOCK_HEIGHT; y++) {
+        for (int x = 0; x < BLOCK_WIDTH; x++) {
+            int screen_x = BLOCK_X + x;
+            int screen_y = BLOCK_Y + y;
+            uint8_t color = (uint8_t)((x + 2 * y) & 0x3f);
+
+            if (x < 3 || y < 3 || x >= BLOCK_WIDTH - 3 || y >= BLOCK_HEIGHT - 3) {
+                color = 0x3f;
+            }
+            put_pixel(screen_x, screen_y, color);
+        }
+    }
+}
+
+int main(void) {
+    syscall(SYS_switch_to_graphics, 0);
+    draw_demo();
+    syscall(SYS_swap_frame, (uintptr_t)frame);
+
+    uint32_t start = time_ms();
+    while ((uint32_t)(time_ms() - start) < 2000) {
+    }
+
+    return 0;
 }