tons more work on modularizing the code

include/BIOS/func/ext_read.inc

@@ -18,6 +18,7 @@
 ; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 ; SOFTWARE.
 
+%ifndef __INC_EXT_READ
 ;Offset	Size	    Description
 ; 0	    1	    size of packet (16 bytes)
 ; 1	    1	    always 0
@@ -52,25 +53,28 @@ endstruc
 ; successfully transferred
 ;
 ;
-; uint8_t read_disk_raw(uint16_t buf_segment, uint16_t buf_offset, uint32_t lba)
-; TODO: this needs validation
+; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset, 
+;                         uint32_t lba,
+;                         uint16_t count, uint16_t drive_num)
+ALIGN 4, db 0x90
 read_disk_raw:
     __CDECL16_ENTRY
-.func:  
+.func:                        
     mov ax, 0x10
     push ax             ; len = 16 bytes
     xor ax, ax
     push ax             ; val = 0
     mov ax, lba_packet
     push ax             ; dest = lba_packet address
-
-    call kmemset        ; uint8_t* kmemset(void* dest, uint8_t val, size_t len);
-    add sp, 0x6
+    call kmemset        
+    add sp, 0x06
 
     mov byte [lba_packet + LBAPkt_t.size], 0x10
-    mov word [lba_packet + LBAPkt_t.xfer_size], 0x0001
 
-    mov dword eax, [bp + 8]
+    mov ax, [bp + 12]
+    mov word [lba_packet + LBAPkt_t.xfer_size], ax
+
+    mov eax, [bp + 8]
     mov dword [lba_packet + LBAPkt_t.lower_lba], eax
 
     mov ax, [bp + 6]
@@ -81,10 +85,26 @@ read_disk_raw:
 
     mov si, lba_packet
     mov ah, 0x42
-    mov dl, byte [fat32_ebpb + FAT32_ebpb_t.drive_number_8]
+
+    ;BUG: still working on getting this passed down correctly, going to hard set it for now.
+    movzx dx, byte [bp + 14]                   
+    and dx, 0x00ff
+    ;xor dl, dl
+    ;mov dl, 0x80
+
     int 0x13
-    jnc read_disk_raw.endp
+    jnc .endf
+
+    %ifdef __STEVIA_MBR
+    ERROR MBR_ERROR_DISK_READ_ERR
+    %elifsef __STEVIA_VBR
+    ERROR VBR_ERROR_DISK_READ_ERR
+    %else
     ERROR STAGE2_MBR_DISK_READ_ERROR
-.endp:
+    %endif
+.endf:
     __CDECL16_EXIT
-    ret
+    ret
+
+%endif
+%define __INC_EXT_READ