lesson 22

22-malloc/README.md

@@ -15,4 +15,10 @@ our first page starts at 0x10000 (as hardcoded on `mem.c`) and
 subsequent `kmalloc()`'s produce a new address which is
 aligned 4096 bytes or 0x1000 from the previous one.
 
+Note that we added a new `strings.c:hex_to_ascii()` for
+nicer printing of hex numbers.
+
+Another cosmetic modification is to rename `types.c` to 
+`type.c` for language consistency.
+
 The rest of the files are unchanged from last lesson.

22-malloc/cpu

@@ -1 +0,0 @@
-../21-shell/cpu

22-malloc/drivers

@@ -1 +0,0 @@
-../21-shell/drivers

22-malloc/kernel/kernel.c

@@ -20,10 +20,10 @@ void user_input(char *input) {
         /* Lesson 22: Code to test kmalloc, the rest is unchanged */
         u32 phys_addr;
         u32 page = kmalloc(1000, 1, &phys_addr);
-        char page_str[16];
-        int_to_ascii(page, page_str);
-        char phys_str[16];
-        int_to_ascii(phys_addr, phys_str);
+        char page_str[16] = "";
+        hex_to_ascii(page, page_str);
+        char phys_str[16] = "";
+        hex_to_ascii(phys_addr, phys_str);
         kprint("Page: ");
         kprint(page_str);
         kprint(", physical address: ");

22-malloc/libc/function.h

@@ -1 +0,0 @@
-../../21-shell/libc/function.h

22-malloc/libc/function.h

@@ -0,0 +1,8 @@
+#ifndef FUNCTION_H
+#define FUNCTION_H
+
+/* Sometimes we want to keep parameters to a function for later use
+ * and this is a solution to avoid the 'unused parameter' compiler warning */
+#define UNUSED(x) (void)(x)
+
+#endif

22-malloc/libc/mem.h

@@ -1,7 +1,7 @@
 #ifndef MEM_H
 #define MEM_H
 
-#include "../cpu/types.h"
+#include "../cpu/type.h"
 
 void memory_copy(u8 *source, u8 *dest, int nbytes);
 void memory_set(u8 *dest, u8 val, u32 len);

22-malloc/libc/string.c

@@ -1 +0,0 @@
-../../21-shell/libc/string.c

22-malloc/libc/string.c

@@ -0,0 +1,77 @@
+#include "string.h"
+#include "../cpu/type.h"
+
+/**
+ * K&R implementation
+ */
+void int_to_ascii(int n, char str[]) {
+    int i, sign;
+    if ((sign = n) < 0) n = -n;
+    i = 0;
+    do {
+        str[i++] = n % 10 + '0';
+    } while ((n /= 10) > 0);
+
+    if (sign < 0) str[i++] = '-';
+    str[i] = '\0';
+
+    reverse(str);
+}
+
+void hex_to_ascii(int n, char str[]) {
+    append(str, '0');
+    append(str, 'x');
+    char zeros = 0;
+
+    s32 tmp;
+    int i;
+    for (i = 28; i > 0; i -= 4) {
+        tmp = (n >> i) & 0xF;
+        if (tmp == 0 && zeros == 0) continue;
+        zeros = 1;
+        if (tmp > 0xA) append(str, tmp - 0xA + 'a');
+        else append(str, tmp + '0');
+    }
+
+    tmp = n & 0xF;
+    if (tmp >= 0xA) append(str, tmp - 0xA + 'a');
+    else append(str, tmp + '0');
+}
+
+/* K&R */
+void reverse(char s[]) {
+    int c, i, j;
+    for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
+        c = s[i];
+        s[i] = s[j];
+        s[j] = c;
+    }
+}
+
+/* K&R */
+int strlen(char s[]) {
+    int i = 0;
+    while (s[i] != '\0') ++i;
+    return i;
+}
+
+void append(char s[], char n) {
+    int len = strlen(s);
+    s[len] = n;
+    s[len+1] = '\0';
+}
+
+void backspace(char s[]) {
+    int len = strlen(s);
+    s[len-1] = '\0';
+}
+
+/* K&R 
+ * Returns <0 if s1<s2, 0 if s1==s2, >0 if s1>s2 */
+int strcmp(char s1[], char s2[]) {
+    int i;
+    for (i = 0; s1[i] == s2[i]; i++) {
+        if (s1[i] == '\0') return 0;
+    }
+    return s1[i] - s2[i];
+}

22-malloc/libc/string.h

@@ -1 +0,0 @@
-../../21-shell/libc/string.h

22-malloc/libc/string.h

@@ -0,0 +1,12 @@
+#ifndef STRINGS_H
+#define STRINGS_H
+
+void int_to_ascii(int n, char str[]);
+void hex_to_ascii(int n, char str[]);
+void reverse(char s[]);
+int strlen(char s[]);
+void backspace(char s[]);
+void append(char s[], char n);
+int strcmp(char s1[], char s2[]);
+
+#endif