Standalone utility functions to be used inside guest

arch/x86/lcd/guest/utility.c

+//
+//  tesla.c
+//  
+//
+//  Created by jithu joseph on 2/28/14.
+//  some standalone utility routines to be used by guest
+//  compile using -static -fno-builtin
+//
+
+//#include <stdio.h>
+typedef unsigned int   uint;
+
+
+unsigned long
+strlen(const char *s)
+{
+    int n;
+    
+    for(n = 0; s[n]; n++)
+    ;
+    return n;
+}
+
+static int lcd_puts(const char *buf)
+{
+	long ret;
+    
+	asm volatile("movq $1, %%rax \n\t" // SYS_write
+                 "movq $1, %%rdi \n\t" // STDOUT
+                 "movq %1, %%rsi \n\t" // string
+                 "movq %2, %%rdx \n\t" // string len
+                 "vmcall \n\t"
+                 "movq %%rax, %0 \n\t" :
+                 "=r" (ret) : "r" (buf), "r" (strlen(buf)) :
+                 "rax", "rdi", "rsi", "rdx");
+    
+	return ret;
+}
+
+static int putc(int fd, const char c)
+{
+	long ret;
+    
+	asm volatile("movq $1, %%rax \n\t" // SYS_write
+                 "movq $1, %%rdi \n\t" // STDOUT
+                 "movq %1, %%rsi \n\t" // string
+                 "movq $1, %%rdx \n\t" // string len
+                 "vmcall \n\t"
+                 "movq %%rax, %0 \n\t" :
+                 "=r" (ret) : "r" (&c) :
+                 "rax", "rdi", "rsi", "rdx");
+    
+	return ret;
+}
+
+static void
+printint(int fd, int xx, int base, int sgn)
+{
+    static char digits[] = "0123456789ABCDEF";
+    char buf[16];
+    int i, neg;
+    uint x;
+    
+    neg = 0;
+    if(sgn && xx < 0){
+        neg = 1;
+        x = -xx;
+    } else {
+        x = xx;
+    }
+    
+    i = 0;
+    do{
+        buf[i++] = digits[x % base];
+    }while((x /= base) != 0);
+    if(neg)
+    buf[i++] = '-';
+    
+    while(--i >= 0)
+    putc(fd, buf[i]);
+}
+
+// Print to the given fd. Only understands %d, %x, %p, %s.
+void
+printf(int fd, char *fmt, ...)
+{
+    char *s;
+    int c, i, state;
+    uint *ap;
+    
+    state = 0;
+    ap = (uint*)(void*)&fmt + 1;
+    for(i = 0; fmt[i]; i++){
+        c = fmt[i] & 0xff;
+        if(state == 0){
+            if(c == '%'){
+                state = '%';
+            } else {
+                putc(fd, c);
+            }
+        } else if(state == '%'){
+            if(c == 'd'){
+                printint(fd, *ap, 10, 1);
+                ap++;
+            } else if(c == 'x' || c == 'p'){
+                printint(fd, *ap, 16, 0);
+                ap++;
+            } else if(c == 's'){
+                s = (char*)*ap;
+                ap++;
+                if(s == 0)
+                s = "(null)";
+                while(*s != 0){
+                    putc(fd, *s);
+                    s++;
+                }
+            } else if(c == 'c'){
+                putc(fd, *ap);
+                ap++;
+            } else if(c == '%'){
+                putc(fd, c);
+            } else {
+                // Unknown % sequence.  Print it to draw attention.
+                putc(fd, '%');
+                putc(fd, c);
+            }
+            state = 0;
+        }
+    }
+}
+
+
+
+