lesson 23, initial commit

23-fixes/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

23-fixes/libc/mem.c

@@ -0,0 +1,33 @@
+#include "mem.h"
+
+void memory_copy(u8 *source, u8 *dest, int nbytes) {
+    int i;
+    for (i = 0; i < nbytes; i++) {
+        *(dest + i) = *(source + i);
+    }
+}
+
+void memory_set(u8 *dest, u8 val, u32 len) {
+    u8 *temp = (u8 *)dest;
+    for ( ; len != 0; len--) *temp++ = val;
+}
+
+/* This should be computed at link time, but a hardcoded
+ * value is fine for now. Remember that our kernel starts
+ * at 0x1000 as defined on the Makefile */
+u32 free_mem_addr = 0x10000;
+/* Implementation is just a pointer to some free memory which
+ * keeps growing */
+u32 kmalloc(u32 size, int align, u32 *phys_addr) {
+    /* Pages are aligned to 4K, or 0x1000 */
+    if (align == 1 && (free_mem_addr & 0xFFFFF000)) {
+        free_mem_addr &= 0xFFFFF000;
+        free_mem_addr += 0x1000;
+    }
+    /* Save also the physical address */
+    if (phys_addr) *phys_addr = free_mem_addr;
+
+    u32 ret = free_mem_addr;
+    free_mem_addr += size; /* Remember to increment the pointer */
+    return ret;
+}

23-fixes/libc/mem.h

@@ -0,0 +1,12 @@
+#ifndef MEM_H
+#define MEM_H
+
+#include "../cpu/type.h"
+
+void memory_copy(u8 *source, u8 *dest, int nbytes);
+void memory_set(u8 *dest, u8 val, u32 len);
+
+/* At this stage there is no 'free' implemented. */
+u32 kmalloc(u32 size, int align, u32 *phys_addr);
+
+#endif

23-fixes/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];
+}

23-fixes/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