MZ is back!HEADmain

1 files changed, 78 insertions, 0 deletions

diff --git a/v4.0/src/BIOS/CLOCKSUB.INC b/v4.0/src/BIOS/CLOCKSUB.INC
new file mode 100644
index 0000000..65b6698
--- /dev/null
+++ b/v4.0/src/BIOS/CLOCKSUB.INC
@@ -0,0 +1,78 @@
+;
+;   date_verify loosely checks bcd date values to be in range in bin_date_time
+;
+date_verify:                                ;
+assume  ds:code,es:nothing
+        cmp     byte ptr bin_date_time+0,20h  ; century check
+        ja      date_error                  ; jmp error
+        jz      century_20                  ; jmp in 20th century
+        cmp     byte ptr bin_date_time+0,19h  ; century check
+        jb      date_error                  ; jmp error
+        cmp     byte ptr bin_date_time+1,80h  ; year check
+        jb      date_error                  ; jmp error
+century_20:                                 ;
+        cmp     byte ptr bin_date_time+1,99h  ; year check
+        ja      date_error                  ; jmp error
+        cmp     byte ptr bin_date_time+2,12h  ; month check
+        ja      date_error                  ; jmp error
+        cmp     byte ptr bin_date_time+2,00h  ; month check
+        jbe     date_error                  ; jmp error
+        cmp     byte ptr bin_date_time+3,31h  ; day check
+        ja      date_error                  ; jmp error
+        cmp     byte ptr bin_date_time+3,00h  ; day check
+        jbe     date_error                  ; jmp error
+        clc                                 ; set success flag
+        ret                                 ;
+date_error:                                 ;
+        stc                                 ; set error flag
+        ret                                 ;
+
+;
+; time_verify very loosely checks bcd date values to be in range in bin_date_time
+;
+time_verify:
+assume  ds:code,es:nothing
+        cmp     byte ptr bin_date_time+0,24H
+        ja      time_error
+        cmp     byte ptr bin_date_time+1,59H
+        ja      time_error
+        cmp     byte ptr bin_date_time+2,59H
+        ja      time_error
+        clc
+        ret
+time_error:
+        stc
+        ret
+
+;
+;   bcd_verify checks values in bin_date_time to be valid
+;   bcd numerals.  carry set if any nibble out of range
+;
+bcd_verify:                     ;
+assume  ds:code,es:nothing
+        mov     cx,4            ; 4 bytes to check
+        mov     bx,offset bin_date_time   ;
+bv_loop:                        ;
+        mov     al,[bx]         ; get a bcd number (0..99)
+        mov     ah,al           ;
+        and     ax,0f00fh       ; 10's place in high ah, 1's in al
+        cmp     al,10           ; is 1's place in range?
+        ja      bv_error        ; jmp out of range
+        shr     ah,1            ; swap nibbles
+        shr     ah,1            ; ...
+        shr     ah,1            ; ...
+        shr     ah,1            ; ...
+        and     ah,0fh          ; get rid of any erroneous bits
+        cmp     ah,10           ; is 10's place in range
+        ja      bv_error        ; jmp out of range
+        inc     bx              ; next byte
+        dec     cx              ;
+        jnz     bv_loop         ;
+        clc                     ; set success flag
+        ret                     ;
+bv_error:                       ;
+        stc                     ; set error flag
+        ret                     ;
+;
+; Dos 3.30 - The real time clock structures were moved to msbio2.asm
+;