With only RISCV64-I extension

1 files changed, 33 insertions, 2 deletions

diff --git a/user/printf.c b/user/printf.c
index 5c5c782..2b9cd06 100644
--- a/user/printf.c
+++ b/user/printf.c
@@ -12,6 +12,36 @@ putc(int fd, char c)
   write(fd, &c, 1);
 }
 
+int mul(int x, int y)
+{
+  int ret = x;
+  for (int tmp = y-1; tmp > 0; tmp--) {
+    // Add higher and lower 16 bits seperately
+    // apparently gcc uses muldi3 builtin while adding long long ints    
+    int rettmp = ret;    
+    ret = (((uint16)(x>>16))+((uint16)(rettmp>>16)));
+    ret += (((uint16)(x&0xffff))+((uint16)(rettmp&0xffff)));
+  }
+  return ret;
+}
+
+int mod(int x, int y)
+{
+  int idx = 0;
+  for (idx = 0; mul(idx, y) <= x; idx++);
+  idx = x-mul((idx-1), y);
+  return idx;
+}
+
+int div(int x, int y)
+{
+  if (y >= x)
+    return 0;
+  int ret = 1;
+  for (; (x=x-y) >= y; ret++);  
+  return ret;
+}
+
 static void
 printint(int fd, int xx, int base, int sgn)
 {
@@ -29,8 +59,9 @@ printint(int fd, int xx, int base, int sgn)
 
   i = 0;
   do{
-    buf[i++] = digits[x % base];
-  }while((x /= base) != 0);
+    buf[i++] = digits[mod(x, base)];
+    x = div(x, base);
+  }while(x != 0);
   if(neg)
     buf[i++] = '-';