The start of some CGA console code.

0f218772 · Silas Boyd-Wickizer · f037a9b1 · 0f218772 · 0f218772 · 0f218772
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,9 @@

 OBJS = \
 	asm.o \
+	cga.o \
 	main.o \
+	string.o \
 	uart.o \
 	trap.o

@@ -45,7 +47,7 @@ clean:
 ifndef CPUS
 CPUS := 2
 endif
-QEMUOPTS = -smp $(CPUS) -m 512 -nographic
+QEMUOPTS = -smp $(CPUS) -m 512

 qemu: kernel
 	$(QEMU) $(QEMUOPTS) -kernel kernel
--- a/cga.c
+++ b/cga.c
+#include "types.h"
+#include "kernel.h"
+
+static volatile u16 *screen = (u16*)(KBASE+0xb8000);
+// Black background, (high intensity) white foreground
+static int color = ((0 << 4) | 15) << 8;
+static int cursor;
+
+extern void setcursor(int);
+
+void
+putsn(const char *s, int n)
+{
+  int i;
+  uint8 *p, *ep;
+
+  p = (uint8*)s;
+  ep = p+n;
+  for(; p < ep; p++) {
+    if(*p == '\n') {
+      cursor += 80 - cursor%80;
+    } else {
+      screen[cursor] = color | *p;
+      cursor++;
+    }
+    if(cursor == 25*80) {
+      memmove((void*)screen+80*2, (void*)screen+80*3, 80*(25-3)*2);
+      for(i=0; i<80; i++)
+        screen[(24*80+i)] = color | ' ' & 0xff;
+      cursor -= 80;
+    }
+  }
+}
+
+static void
+cgaputs(const char *s)
+{
+  putsn(s, strlen(s));
+}
+
+void
+panic(const char *s)
+{
+  cgaputs("panic: ");
+  cgaputs(s);
+  cgaputs("\n");
+  setcursor(cursor);
+  for(;;)
+    screen[0] = screen[0];
+}
+
+void
+initcga(void)
+{
+  // Assume boot.S set up the screen.
+  // We're just taking over the cursor position.
+  cursor = 2*80;
+  setcursor(cursor);
+  
+  cgaputs("booting...\n");
+  setcursor(cursor);
+}
--- a/kernel.h
+++ b/kernel.h
 #include "types.h"
+
+#define KBASE 0xFFFFFFFF80000000ull
+#define KADDR(x) ((void*)(KBASE+(uintptr)(x)))
+#define PADDR(x) ((uintptr)(x) - KBASE)
+#define PGSIZE (2*1024*1024ull)
+
+#define KCSEG (2<<3)  /* kernel code segment */
+#define KDSEG (3<<3)  /* kernel data segment */
+
+#define nil ((void*)0)
+
+void	memmove(void *dst, void *src, int64 n);
+int strlen(const char*);
--- a/main.c
+++ b/main.c
 #include "types.h"
 #include "multiboot.h"

-extern void uartinit(void);
+extern void inituart(void);
+extern void initcga(void);

 void
 cmain(void)
 {
-  uartinit();
+  inituart();
+  initcga();
 }
--- a/string.c
+++ b/string.c
@@ -2,16 +2,16 @@
 #include "x86.h"

 void*
-memset(void *dst, int c, uint n)
+memset(void *dst, int c, u32 n)
 {
  stosb(dst, c, n);
  return dst;
 }

 int
-memcmp(const void *v1, const void *v2, uint n)
+memcmp(const void *v1, const void *v2, u32 n)
 {
-  const uchar *s1, *s2;
+  const u8 *s1, *s2;
  
  s1 = v1;
  s2 = v2;
@@ -25,7 +25,7 @@ memcmp(const void *v1, const void *v2, uint n)
 }

 void*
-memmove(void *dst, const void *src, uint n)
+memmove(void *dst, const void *src, u32 n)
 {
  const char *s;
  char *d;
@@ -46,23 +46,23 @@ memmove(void *dst, const void *src, uint n)

 // memcpy exists to placate GCC.  Use memmove.
 void*
-memcpy(void *dst, const void *src, uint n)
+memcpy(void *dst, const void *src, u32 n)
 {
  return memmove(dst, src, n);
 }

 int
-strncmp(const char *p, const char *q, uint n)
+strncmp(const char *p, const char *q, u32 n)
 {
  while(n > 0 && *p && *p == *q)
    n--, p++, q++;
  if(n == 0)
    return 0;
-  return (uchar)*p - (uchar)*q;
+  return (u8)*p - (u8)*q;
 }

 char*
-strncpy(char *s, const char *t, int n)
+strncpy(char *s, const char *t, u32 n)
 {
  char *os;
  
@@ -76,7 +76,7 @@ strncpy(char *s, const char *t, int n)

 // Like strncpy but guaranteed to NUL-terminate.
 char*
-safestrcpy(char *s, const char *t, int n)
+safestrcpy(char *s, const char *t, u32 n)
 {
  char *os;
  
@@ -104,6 +104,5 @@ strcmp(const char *p, const char *q)
 {
  while(*p && *p == *q)
    p++, q++;
-  return (uchar)*p - (uchar)*q;
+  return (u8)*p - (u8)*q;
 }
-
--- a/uart.c
+++ b/uart.c
@@ -19,7 +19,7 @@ uartputc(int c)
 }

 void
-uartinit(void)
+inituart(void)
 {
    char *p;


--- a/vmx.h
+++ b/vmx.h
@@ -19,7 +19,6 @@ uint8	inb(uint16);
 void	outb(uint16, uint8);
 void	microdelay(int);
 uint32	readeflags(void);
-void	setcursor(int);
 void	memmove(void *dst, void *src, int64 n);
 int memcmp(const void*, const void*, int64);
 void	hlt(void);

--- a/x86.h
+++ b/x86.h
@@ -17,6 +17,15 @@ outb(u16 port, u8 data)
 }

 static inline void
+stosb(void *addr, int data, int cnt)
+{
+  __asm volatile("cld; rep stosb" :
+                 "=D" (addr), "=c" (cnt) :
+                 "0" (addr), "1" (cnt), "a" (data) :
+                 "memory", "cc");
+}
+
+static inline void
 microdelay(u32 delay)
 {