Lecture 112 - Creating some important stdlib functions

programs/blank/blank.c

@@ -1,9 +1,18 @@
 #include "peachos.h"
 #include "stdlib.h"
 #include "stdio.h"
+#include "string.h"
 int main(int argc, char** argv)
 {
-    printf("My age is %i\n", 98);
+    char words[] = "hello how are you";
+
+    const char* token = strtok(words, " ");
+    while(token)
+    {
+        printf("%s\n", token);
+        token = strtok(NULL, " ");
+    }
+
     while(1) 
     {
     }

programs/stdlib/Makefile

@@ -1,4 +1,4 @@
-FILES=./build/start.o ./build/peachos.asm.o ./build/peachos.o ./build/stdlib.o ./build/stdio.o
+FILES=./build/start.o ./build/peachos.asm.o ./build/peachos.o ./build/stdlib.o ./build/stdio.o ./build/string.o ./build/memory.o
 INCLUDES=-I./src
 FLAGS= -g -ffreestanding -falign-jumps -falign-functions -falign-labels -falign-loops -fstrength-reduce -fomit-frame-pointer -finline-functions -Wno-unused-function -fno-builtin -Werror -Wno-unused-label -Wno-cpp -Wno-unused-parameter -nostdlib -nostartfiles -nodefaultlibs -Wall -O0 -Iinc
 
@@ -21,6 +21,14 @@ all: ${FILES}
 	i686-elf-gcc ${INCLUDES} $(FLAGS) -std=gnu99 -c ./src/stdio.c -o ./build/stdio.o
 
 
+./build/string.o: ./src/string.c
+	i686-elf-gcc ${INCLUDES} $(FLAGS) -std=gnu99 -c ./src/string.c -o ./build/string.o
+
+./build/memory.o: ./src/memory.c
+	i686-elf-gcc ${INCLUDES} $(FLAGS) -std=gnu99 -c ./src/memory.c -o ./build/memory.o
+
+
+
 clean:
 	rm -rf ${FILES}
 	rm ./stdlib.elf

programs/stdlib/src/memory.c

@@ -0,0 +1,37 @@
+#include "memory.h"
+
+void* memset(void* ptr, int c, size_t size)
+{
+    char* c_ptr = (char*) ptr;
+    for (int i = 0; i < size; i++)
+    {
+        c_ptr[i] = (char) c;
+    }
+    return ptr;
+}
+
+int memcmp(void* s1, void* s2, int count)
+{
+    char* c1 = s1;
+    char* c2 = s2;
+    while(count-- > 0)
+    {
+        if (*c1++ != *c2++)
+        {
+            return c1[-1] < c2[-1] ? -1 : 1;
+        }
+    }
+
+    return 0;
+}
+
+void* memcpy(void* dest, void* src, int len)
+{
+    char *d = dest;
+    char *s = src;
+    while(len--)
+    {
+        *d++ = *s++;
+    }
+    return dest;
+}

programs/stdlib/src/memory.h

@@ -0,0 +1,8 @@
+#ifndef PEACHOS_MEMORY_H
+#define PEACHOS_MEMORY_H
+
+#include <stddef.h>
+void* memset(void* ptr, int c, size_t size);
+int memcmp(void* s1, void* s2, int count);
+void* memcpy(void* dest, void* src, int len);
+#endif

programs/stdlib/src/string.c

@@ -0,0 +1,176 @@
+#include "string.h"
+
+char tolower(char s1)
+{
+    if (s1 >= 65 && s1 <= 90)
+    {
+        s1 += 32;
+    }
+
+    return s1;
+}
+
+int strlen(const char* ptr)
+{
+    int i = 0;
+    while(*ptr != 0)
+    {
+        i++;
+        ptr += 1;
+    }
+
+    return i;
+}
+
+int strnlen(const char* ptr, int max)
+{
+    int i = 0;
+    for (i = 0; i < max; i++)
+    {
+        if (ptr[i] == 0)
+            break;
+    }
+
+    return i;
+}
+
+int strnlen_terminator(const char* str, int max, char terminator)
+{
+    int i = 0;
+    for(i = 0; i < max; i++)
+    {
+        if (str[i] == '\0' || str[i] == terminator)
+            break;
+    }
+
+    return i;
+}
+
+int istrncmp(const char* s1, const char* s2, int n)
+{
+    unsigned char u1, u2;
+    while(n-- > 0)
+    {
+        u1 = (unsigned char)*s1++;
+        u2 = (unsigned char)*s2++;
+        if (u1 != u2 && tolower(u1) != tolower(u2))
+            return u1 - u2;
+        if (u1 == '\0')
+            return 0;
+    }
+
+    return 0;
+}
+int strncmp(const char* str1, const char* str2, int n)
+{
+    unsigned char u1, u2;
+
+    while(n-- > 0)
+    {
+        u1 = (unsigned char)*str1++;
+        u2 = (unsigned char)*str2++;
+        if (u1 != u2)
+            return u1 - u2;
+        if (u1 == '\0')
+            return 0;
+    }
+
+    return 0;
+}
+
+char* strcpy(char* dest, const char* src)
+{
+    char* res = dest;
+    while(*src != 0)
+    {
+        *dest = *src;
+        src += 1;
+        dest += 1;
+    }
+
+    *dest = 0x00;
+
+    return res;
+}
+
+char* strncpy(char* dest, const char* src, int count)
+{
+    int i = 0;
+    for (i = 0; i < count-1; i++)
+    {
+        if (src[i] == 0x00)
+            break;
+
+        dest[i] = src[i];
+    }
+
+    dest[i] = 0x00;
+    return dest;
+}
+
+bool isdigit(char c)
+{
+    return c >= 48 && c <= 57;
+}
+int tonumericdigit(char c)
+{
+    return c - 48;
+}
+
+char* sp = 0;
+char* strtok(char* str, const char* delimiters)
+{
+    int i = 0;
+    int len = strlen(delimiters);
+    if (!str && !sp)
+        return 0;
+
+    if (str && !sp)
+    {
+        sp = str;
+    }
+
+    char* p_start = sp;
+    while(1)
+    {
+        for (i = 0; i < len; i++)
+        {
+            if(*p_start == delimiters[i])
+            {
+                p_start++;
+                break;
+            }
+        }
+
+        if (i == len)
+        {
+            sp = p_start;
+            break;
+        }
+    }
+
+    if (*sp == '\0')
+    {
+        sp = 0;
+        return sp;
+    }
+
+    // Find end of substring
+    while(*sp != '\0')
+    {
+        for (i = 0; i < len; i++)
+        {
+            if (*sp == delimiters[i])
+            {
+                *sp = '\0';
+                break;
+            }
+        }
+
+        sp++;
+        if (i < len)
+            break;
+    }
+
+    return p_start;
+}

programs/stdlib/src/string.h

@@ -0,0 +1,18 @@
+#ifndef PEACHOS_STRING_H
+#define PEACHOS_STRING_H
+
+#include <stdbool.h>
+
+char tolower(char s1);
+int strlen(const char* ptr);
+int strnlen(const char* ptr, int max);
+int strnlen_terminator(const char* str, int max, char terminator);
+int istrncmp(const char* s1, const char* s2, int n);
+int strncmp(const char* str1, const char* str2, int n);
+char* strcpy(char* dest, const char* src);
+char* strncpy(char* dest, const char* src, int count);
+bool isdigit(char c);
+int tonumericdigit(char c);
+char* strtok(char* str, const char* delimiters);
+
+#endif