[optimization] printf and puts should print full string as one syscall

Author: scopeInfinity

src/kernel/syscall/console.c

@@ -4,12 +4,30 @@
 
 #include <lib/utils/output.h>
 
-int _console_putchar(char c) {
+#define CONSOLE_PUTS_BUFFER_SIZE 128
+
+static int _console_putchar(char c) {
     print_char(c);
     return 0;
 }
 
-int _console_clrscr() {
+static int _console_puts_buffer(int user_ds, const char *__us_str, int len) {
+    char str[CONSOLE_PUTS_BUFFER_SIZE]={0};
+    while (len > 0) {
+        int sub_len = min(CONSOLE_PUTS_BUFFER_SIZE, len);
+        syscall_strncpy_user_to_kernel(user_ds, __us_str, str, sub_len);
+
+        for(int i=0;i<sub_len;i++) {
+            print_char(str[i]);
+        }
+
+        len -= sub_len;
+        __us_str += sub_len;
+    }
+    return 0;
+}
+
+static int _console_clrscr() {
     print_rectangle(0, 0, TEXT_WINDOW_WIDTH-1, TEXT_WINDOW_HEIGHT-1);
     move_xy(0,0);
 }
@@ -20,7 +38,10 @@ int syscall_3_console(int operation, int a1, int a2, int a3, int user_ds) {
             return _console_clrscr();
         case SYSCALL_CONSOLE_SUB_PUTCHAR:
             return _console_putchar((char)a1);
+        case SYSCALL_CONSOLE_SUB_PUTS_BUFFER:
+            return _console_puts_buffer(user_ds, (const char*)a1, a2);
     }
     return -1;
 }
 
+#undef CONSOLE_PUTS_BUFFER_SIZE

src/usr/include/stdio.h

@@ -4,9 +4,12 @@
 
 #define SYSCALL_CONSOLE_SUB_CLRSCR       0
 #define SYSCALL_CONSOLE_SUB_PUTCHAR      1
+#define SYSCALL_CONSOLE_SUB_PUTS_BUFFER  2
 
 int putchar(int c);
 int puts(const char *s);
+
+int snprintf(char *s, size_t n, const char *fmt, ...);
 int printf(const char *strfmt, ...);
 
 char* gets (char *s);

src/usr/lib/stdio.c

@@ -12,63 +12,86 @@ int putchar(int c) {
 
 int puts(const char *s) {
     if(!s) return 0;
-    int c = 0;
-    while ((*s)!='\0') {
-        putchar(*(s++));
-        c++;
-    }
-    return c;
+    int len = strlen(s);
+    return SYSCALL_A3(SYSCALL_CONSOLE, SYSCALL_CONSOLE_SUB_PUTS_BUFFER, s, len);
 }
 
-int printf(const char *fmt, ...) {
-    int len = 0;
-    int rv = 0;
-    va_list args;
-    va_start(args, fmt);
-    for(;rv >= 0 && (*fmt)!='\0' ; fmt++) {
+static int vsnprintf(char *s, size_t n, const char *fmt, va_list args) {
+    if(n==0) return 0;
+    if(n==1) {
+        s[0]='\0';
+        return 0;
+    }
+    n--; // count non-null char
+
+    size_t len = 0;
+    int err = 0;
+    for(;err >= 0 && len<n && (*fmt)!='\0' ; fmt++) {
         if((*fmt)!='%') {
-            putchar((*fmt));
-            len++;
+            s[len++] = (*fmt);
             continue;
         }
         fmt++;
         if((*fmt)=='\0') break;
 
         // formatting options
         switch(*fmt) {
+            char *innerstr;
             char sbuffer[68];
             case '%':
-                putchar('%');
-                len++;
+                s[len++]='%';
                 break;
             case 'c':
-                putchar(va_arg(args, char));
-                len++;
+                s[len++]=va_arg(args, char);
                 break;
             case 's':
-                rv = puts(va_arg(args, const char*));
-                if(rv>0) len+=rv;
+                innerstr = va_arg(args, const char*);
+                while (len<n && (*innerstr)!='\0') {
+                    s[len++]=*(innerstr++);
+                }
                 break;
             case 'd':
                 itoa(va_arg(args, int), sbuffer, 10);
-                rv = puts(sbuffer);
-                if(rv>0) len+=rv;
+                innerstr = sbuffer;
+                while (len<n && (*innerstr)!='\0') {
+                    s[len++]=*(innerstr++);
+                }
                 break;
             case 'X':
             case 'x':  // not an priority for now :)
                 itoa(va_arg(args, int), sbuffer, 16);
-                rv = puts(sbuffer);
-                if(rv>0) len+=rv;
+                innerstr = sbuffer;
+                while (len<n && (*innerstr)!='\0') {
+                    s[len++]=*(innerstr++);
+                }
                 break;
             default:
-                return -1;  // invalid format char
+                err = -1;  // invalid format char, terminate
         }
     }
-    va_end(args);
-    if(rv < 0) return rv;
+    s[len]='\0';
+    if(err != 0) return err;
     return len;
 }
 
+int snprintf(char *s, size_t n, const char *fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+    int ret = vsnprintf(s, n, fmt, args);
+    va_end(args);
+    return ret;
+}
+
+int printf(const char *fmt, ...) {
+    // limitation: it won't print more than 256 bytes in one go.
+    char buffer[256];
+    va_list args;
+    va_start(args, fmt);
+    int ret = vsnprintf(buffer, sizeof(buffer), fmt, args);
+    va_end(args);
+    return puts(buffer);
+}
+
 char* gets(char *s) {
     char *og = s;
     while (1) {

src/usr/local/src/multiprocessing.c

@@ -12,14 +12,15 @@ int main(int argc,char *argv[]) {
         // child process
         am_i_child=1;
         printf("child process: says Hi\n");
+        yield(); // force process scheduler
     } else {
         am_i_child=0;
         // parent process
         printf("parent process: says Hi\n");
         printf("will for child process to exit\n");
         waitpid(pid);
     }
-    printf("process exiting. Am I child process=%s\n", (am_i_child)?"Yes":"No");
+    printf("process exiting. Is correct process the child: %s\n", (am_i_child)?"Yes":"No");
 
     return 0;
 }