source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Libraries/prntbios.asm@ 19

Last change on this file since 19 was 3, checked in by Tomi Tilli, 14 years ago
File size: 2.8 KB
RevLine 
[3]1; File name : prntbios.asm
2; Project name : Print library
3; Created date : 7.12.2009
4; Last update : 17.1.2010
5; Author : Tomi Tilli
6; Description : ASM library to for character and string
7; printing using BIOS.
8
9;--------------- Equates -----------------------------
10
11; Int 10h (BIOS) functions
12FN_BIOS_WR_CHAR_TEL EQU 0Eh ; Teletype Output
13
14
15;-------------- Public functions ---------------------
16; Section containing code
17SECTION .text
18
19;--------------------------------------------------------------------
20; Prints character. All character printing functions must
21; use this macro to print characters (so printing implementation
22; can be easily modified when needed).
23;
24; PRINT_CHAR
25; Parameters:
26; DL: Character to print
27; Returns:
28; Nothing
29; Corrupts registers:
30; AX
31;--------------------------------------------------------------------
32%macro PRINT_CHAR 0
33 call Print_BiosTeleChar
34%endmacro
35
36ALIGN JUMP_ALIGN
37Print_BiosTeleChar:
38 push bp ; Save because of buggy BIOSes
39 push bx
40 mov ah, FN_BIOS_WR_CHAR_TEL
41 mov al, dl ; Copy char to write
42 xor bx, bx ; Page 0
43 int 10h
44 pop bx
45 pop bp
46 ret
47
48
49;--------------------------------------------------------------------
50; Prints string. All string printing functions must
51; use this macro to print strings (so printing implementation
52; can be easily modified when needed).
53;
54; PRINT_STR
55; Parameters:
56; DS:DX: Ptr to STOP terminated string
57; Returns:
58; Nothing
59; Corrupts registers:
60; AX
61;--------------------------------------------------------------------
62%macro PRINT_STR 0
63 push dx
64 call Print_BiosTeleStr
65 pop dx
66%endmacro
67
68
69;--------------------------------------------------------------------
70; Prints string and returns number of characters printed.
71; All string printing functions must use this macro to print strings
72; (so printing implementation can be easily modified when needed).
73;
74; PRINT_STR_LEN
75; Parameters:
76; DS:DX: Ptr to STOP terminated string
77; Returns:
78; DX: Number of characters printed
79; Corrupts registers:
80; AX
81;--------------------------------------------------------------------
82%macro PRINT_STR_LEN 0
83 call Print_BiosTeleStr
84%endmacro
85
86ALIGN JUMP_ALIGN
87Print_BiosTeleStr:
88 push bp ; Save because of buggy BIOSes
89 push si
90 push bx
91 mov si, dx ; Copy offset to string
92 xor dx, dx ; Zero char counter
93 xor bx, bx ; Page 0
94 cld ; LODSB to increment SI
95ALIGN JUMP_ALIGN
96.CharLoop:
97 lodsb ; Load char from [DS:SI] to AL
98 cmp al, STOP ; End of string?
99 je .Return ; If so, return
100 mov ah, FN_BIOS_WR_CHAR_TEL ; Some BIOSes corrupts AX when returning
101 int 10h
102 inc dx ; Increment chars printed
103 jmp .CharLoop ; Loop while chars left
104ALIGN JUMP_ALIGN
105.Return:
106 pop bx
107 pop si
108 pop bp
109 ret
Note: See TracBrowser for help on using the repository browser.