void strcpy (destination, destination_segment, source, source_segment );
int strlen (source, source_segment);
void memcpy (destination, destination_segment, source, source_segment, num_bytes );

int strlen (source, source_segment)
{
    #asm
    #define strlen_SOURCE 4[bp];
    #define strlen_SOURCE_SEGMENT 6[bp];
    push bp
    mov bp,sp
    push ds
    push bx

    mov ax, strlen_SOURCE_SEGMENT
    mov ds, ax

    mov bx, strlen_SOURCE

    label_strlen:
       mov cx, #0x0            ; Set counte to zero
    .label_strlen_loop: 
       mov BYTE al, [bx] 
       cmp al, #0x0 
       je .label_strlen_done 
       inc cx                  ; Count 1
       inc bx                  ; Look at next char
       jmp .label_strlen_loop
    .label_strlen_done:
       mov ax, cx 
    
    pop bx
    pop ds
    pop bp
    #endasm
}

void strcpy (destination, destination_segment, source, source_segment )
char *destination;
int destination_segment;
char *source;
int source_segment;
{
    #asm
    ; copy two strings
    ; IN si: the first (zero terminated) string
    ; IN di: the second (zero terminated) string
    ; OUT SF and ZF (same semantics as cmp)
    
    #define DESTINATION 4[bp];
    #define DESTINATION_SEGMENT 6[bp];
    #define SOURCE 8[bp];
    #define SOURCE_SEGMENT 10[bp];

    push bp
    mov bp,sp
    label_strcpy:
        push ax
        push bx
        push di
        push es
        push si
        push ds
        mov ax, DESTINATION; 
        mov di, ax
        mov ax, DESTINATION_SEGMENT; 
        mov es, ax
        mov ax, SOURCE; 
        mov si, ax
        mov ax, SOURCE_SEGMENT; 
        mov ds, ax
        mov cx, 0x050 // TODO(Jørn) Hardcded number of bytes to copy
    .label_strcpy_loop:
        movsb
        cmp cx, 0x0
        je .label_strcpy_end
        dec cx
        jmp .label_strcpy_loop
    .label_strcpy_end:
        pop ds
        pop si
        pop es
        pop di
        pop bx
        pop ax
        pop bp

    #endasm
}

void memcpy (destination, destination_segment, source, source_segment, num_bytes)
void *destination;
int destination_segment;
void *source;
int source_segment;
int num_bytes;
{
    #asm
    ; copy two strings
    ; IN si: the first (zero terminated) string
    ; IN di: the second (zero terminated) string
    ; OUT SF and ZF (same semantics as cmp)
    
    #define DESTINATION 4[bp];
    #define DESTINATION_SEGMENT 6[bp];
    #define SOURCE 8[bp];
    #define SOURCE_SEGMENT 10[bp];
    #define NUM_BYTES 12[bp];

    push bp
    mov bp,sp
    label_memcpy:
        push ax
        push bx
        push di
        push es
        push si
        push ds
        mov ax, DESTINATION; 
        mov di, ax
        mov ax, DESTINATION_SEGMENT; 
        mov es, ax
        mov ax, SOURCE; 
        mov si, ax
        mov ax, SOURCE_SEGMENT; 
        mov ds, ax
        mov cx, NUM_BYTES
    .label_memcpy_loop:
        movsb
        cmp cx, 0x0
        je .label_memcpy_end
        dec cx
        jmp .label_memcpy_loop
    .label_memcpy_end:
        pop ds
        pop si
        pop es
        pop di
        pop bx
        pop ax
        pop bp

    #endasm
}