Merge pull request #4 from Richard-Qin-001/dev/shell

Rebuilt the system's underlying structure; it is now stable enough to merge. 

The system now supports a read-only file system and has a simple shell implemented.

1 files changed, 175 insertions, 46 deletions

diff --git a/src/drivers/uart.cc b/src/drivers/uart.cc
index 367f442..4064b16 100644
--- a/src/drivers/uart.cc
+++ b/src/drivers/uart.cc
@@ -1,77 +1,206 @@
 #include "drivers/uart.h"
-#include "common/types.h"
-#include "kernel/config.h"
+#include "kernel/riscv.h"
+#include "kernel/spinlock.h"
+#include "kernel/proc.h"
+#include "kernel/mm.h"
+#include "lib/string.h"
 
-// #define UART0_BASE          0x10000000L
-
-#define UART_RBR            0x00 // Receiver Buffer Register (Read)
-#define UART_THR            0x00 // Transmitter Holding Register (Write)
-#define UART_IER            0x01 // Interrupt Enable Register
-#define UART_FCR            0x02 // FIFO Control Register
-#define UART_LCR            0x03 // Line Control Register
-#define UART_LSR            0x05 // Line Status Register
-
-#define UART_LSR_RX_READY   0x01
-#define UART_LSR_TX_EMPTY   0x20
-
-namespace Drivers{
-    inline volatile uint8_t &reg(uint32_t offset)
+namespace Drivers
+{
+    // Circular buffer structure
+    struct
     {
-        return *reinterpret_cast<volatile uint8_t *>(g_uart_base + offset);
-    }
+        Spinlock lock;
+        char buf[UART_RX_BUF_SIZE];
+        uint32 r; // read index
+        uint32 w; // write index
+    } uart_rx;
+
+    Spinlock uart_tx_lock;
 
     void uart_init()
     {
-        
-        if (g_uart_base == 0)
-            return;
+        uart_rx.lock.init("uart_rx");
+        uart_tx_lock.init("uart_tx");
+        uart_rx.r = 0;
+        uart_rx.w = 0;
+
+        // Disable interrupts and configure
+        *(volatile uint8 *)(UART0 + IER) = 0x00;
 
-        reg(UART_IER) = 0x00;
+        // Enter baud rate setting mode (LCR_DLAB) = 0x80;
+        *(volatile uint8 *)(UART0 + LCR) = 0x80;
+        *(volatile uint8 *)(UART0 + 0) = 0x03; // DLL: 38.4K baud
+        *(volatile uint8 *)(UART0 + 1) = 0x00; // DLM
 
-        reg(UART_LCR) = 0x80;
-        reg(0x00) = 0x03;
-        reg(0x01) = 0x00;
+        // Exit baud rate setting, set 8-bit word length, no parity
+        *(volatile uint8 *)(UART0 + LCR) = 0x03;
 
-        reg(UART_LCR) = 0x03;
+        // Reset and enable FIFO
+        *(volatile uint8 *)(UART0 + FCR) = 0x07;
 
-        reg(UART_FCR) = 0x07; // Enable FIFO, clear TX/RX queues
+        // Enable Receive Data Available Interrupt
+        *(volatile uint8 *)(UART0 + IER) = 0x01;
     }
 
     void uart_putc(char c)
     {
-        if (c == '\n')
+        uart_tx_lock.acquire();
+        while ((*(volatile uint8 *)(UART0 + LSR) & LSR_TX_IDLE) == 0)
+            ;
+        *(volatile uint8 *)(UART0 + THR) = c;
+        uart_tx_lock.release();
+    }
+
+    void uart_puts(const char *s)
+    {
+        while (*s)
+            uart_putc(*s++);
+    }
+
+    void uart_put_int(int val)
+    {
+        char buf[16];
+        int i = 0;
+        if (val == 0)
         {
-            uart_putc('\r');
+            uart_puts("0");
+            return;
         }
-
-        while ((reg(UART_LSR) & UART_LSR_TX_EMPTY) == 0)
+        if (val < 0)
         {
-
+            uart_puts("-");
+            val = -val;
         }
+        while (val > 0)
+        {
+            buf[i++] = (val % 10) + '0';
+            val /= 10;
+        }
+        while (i > 0)
+        {
+            uart_putc(buf[--i]);
+        }
+    }
 
-        reg(UART_THR) = c;
+    void print_hex(uint64 val)
+    {
+        char hex[] = "0123456789ABCDEF";
+        uart_puts("0x");
+        for (int i = 60; i >= 0; i -= 4)
+        {
+            uart_putc(hex[(val >> i) & 0xF]);
+        }
     }
 
-    void uart_puts(const char *s)
+    void uart_intr()
     {
-        while (*s)
+        uart_rx.lock.acquire();
+
+        while (1)
         {
-            uart_putc(*s++);
+            if ((*(volatile uint8 *)(UART0 + LSR) & LSR_RX_READY) == 0)
+                break;
+
+            char c = *(volatile uint8 *)(UART0 + RHR);
+
+            uart_rx.buf[uart_rx.w % UART_RX_BUF_SIZE] = c;
+            uart_rx.w++;
+
+            ProcManager::wakeup(&uart_rx);
         }
+
+        uart_rx.lock.release();
     }
 
-    void print_hex(uint64_t val)
+    // Modern console read: Line buffering + Editing Keys + Echo
+    int console_read(uint64 target, int len)
     {
-        char buf[20];
-        const char *digits = "0123456789ABCDEF";
-        buf[0] = '0';
-        buf[1] = 'x';
-        for (int i = 0; i < 16; i++)
+        struct Proc *p = myproc();
+        int target_idx = 0;
+
+        uart_rx.lock.acquire();
+
+        while (target_idx < len)
         {
-            buf[17 - i] = digits[val & 0xF];
-            val >>= 4;
+            while (uart_rx.r == uart_rx.w)
+            {
+                if (p->xstate != 0)
+                {
+                    uart_rx.lock.release();
+                    return -1;
+                }
+                ProcManager::sleep(&uart_rx, &uart_rx.lock);
+            }
+
+            char c = uart_rx.buf[uart_rx.r % UART_RX_BUF_SIZE];
+            uart_rx.r++;
+
+            uart_rx.lock.release();
+
+            // 1. Handle Backspace (127 or \b)
+            if (c == 127 || c == '\b')
+            {
+                if (target_idx > 0)
+                {
+                    // Erase character from screen: Backspace, Space, Backspace
+                    uart_putc('\b');
+                    uart_putc(' ');
+                    uart_putc('\b');
+                    target_idx--;
+                }
+                uart_rx.lock.acquire();
+                continue;
+            }
+
+            // 2. Handle Ctrl+U (Kill Line)
+            if (c == 0x15)
+            {
+                while (target_idx > 0)
+                {
+                    uart_putc('\b');
+                    uart_putc(' ');
+                    uart_putc('\b');
+                    target_idx--;
+                }
+                uart_rx.lock.acquire();
+                continue;
+            }
+
+            // 3. Handle Ctrl+L (Clear Screen)
+            if (c == 0x0C)
+            {
+                uart_puts(ANSI_CLEAR);
+                uart_puts("$ ");
+                uart_rx.lock.acquire();
+                continue;
+            }
+
+            // 4. Handle Return (CR -> LF)
+            if (c == '\r')
+            {
+                c = '\n';
+            }
+
+            // Echo back to user
+            // uart_putc(c);
+
+            if (VM::copyout(p->pagetable, target + target_idx, &c, 1) < 0)
+            {
+                return -1;
+            }
+
+            target_idx++;
+
+            if (c == '\n')
+            {
+                return target_idx;
+            }
+
+            uart_rx.lock.acquire();
         }
-        buf[18] = 0;
-        Drivers::uart_puts(buf);
+
+        uart_rx.lock.release();
+        return target_idx;
     }
 }
\ No newline at end of file