|
Table of Content | |
|
Table of Content | |
| CHAPTER SEVEN: THE UCR STANDARD LIBRARY (Part 2) |
| 7.2 - Sample
Programs 7.2.1 - Stripped SHELL.ASM File 7.2.2 - Numeric I/O |
7.2 Sample Programs |
The following programs demonstrate some common operations that use the Standard Library.
; Sample Starting SHELL.ASM file
;
; Randall Hyde
; Version 1.0
; 2/6/96
;
; This file shows what the SHELL.ASM file looks like without
; the superfluous comments that explain where to place objects
; in the source file. Your programs should likewise begin
; with a stripped version of the SHELL.ASM file. After all
; the comments in the original SHELL.ASM file are four *your*
; consumption
not to be read by someone who sees the program
; you wind up writing.
.xlist
include stdlib.a
includelib stdlib.lib
.list
dseg segment para public 'data'
dseg ends
cseg segment para public 'code'
assume cs:cseg
ds:dseg
Main proc
mov ax
dseg
mov ds
ax
mov es
ax
meminit
Quit: ExitPgm
Main endp
cseg ends
sseg segment para stack 'stack'
stk db 1024 dup ("stack ")
sseg ends
zzzzzzseg segment para public 'zzzzzz'
LastBytes db 16 dup (?)
zzzzzzseg ends
end Main
7.2.2 Numeric I/O
; Pgm7_2.asm - Numeric I/O.
;
; Randall Hyde
; 2/6/96
;
; The standard library routines do not provide simple to use numeric input
; routines. This code demonstrates how to read decimal and hexadecimal values
; from the user using the Getsm
ATOI
ATOU
ATOH
IsDigit
and IsXDigit routines.
.xlist
include stdlib.a
includelib stdlib.lib
.list
dseg segment para public 'data'
inputLine byte 128 dup (0)
SignedInteger sword ?
UnsignedInt word ?
HexValue word ?
dseg ends
cseg segment para public 'code'
assume cs:cseg
ds:dseg
Main proc
mov ax
dseg
mov ds
ax
mov es
ax
meminit
; Read a signed integer value from the user.
InputInteger: print
byte "Input a signed integer value: "
0
lesi inputLine ;Point es:di at inputLine buffer
gets ;Read a line of text from the user.
mov bx
-1
SkipSpcs1: inc bx
cmp inputLine[bx]
' ' ;Skip over any spaces.
je SkipSpcs1
cmp inputLine[bx]
'-' ;See if it's got a minus sign
jne NoSign
inc bx ;Skip if a negative number
NoSign: dec bx ;Back up one place.
TestDigs: inc bx ;Move on to next char
mov al
inputLine[bx]
IsDigit ;See if it's a decimal digit.
je TestDigs ;Repeat process if it is.
cmp inputLine[bx]
' ' ;See if we end with a
je GoodDec ; reasonable character.
cmp inputLine[bx]
'
'
je GoodDec
cmp inputLine[bx]
0 ;Input line ends with a zero.
je GoodDec
printf
byte "'%s' is an illegal signed integer. "
byte "Please reenter."
cr
lf
0
dword inputLine
jmp InputInteger
; Okay
all the characters are cool
let's do the conversion here. Note that
; ES:DI is still pointing at inputLine.
GoodDec: ATOI ;Do the conversion
mov SignedInteger
ax ;Save the value away.
; Read an unsigned integer value from the user.
InputUnsigned: print
byte "Input an unsigned integer value: "
0
lesi inputLine ;Point es:di at inputLine buffer
gets ;Read a line of text from the user.
; Note the sneakiness in the following code. It starts with an index of -2
; and then increments it by one. When accessing data in this loop it compares
; against locatoin inputLine[bx+1] which effectively starts bx at zero. In the
; "TestUnsigned" loop below
this code increments bx again so that bx then
; contains the index into the string when the action is occuring.
mov bx
-2
SkipSpcs2: inc bx
cmp inputLine[bx+1]
' ' ;Skip over any spaces.
je SkipSpcs2
TestUnsigned: inc bx ;Move on to next char
mov al
inputLine[bx]
IsDigit ;See if it's a decimal digit.
je TestUnsigned ;Repeat process if it is.
cmp inputLine[bx]
' ' ;See if we end with a
je GoodUnSigned ; reasonable character.
cmp inputLine[bx]
'
'
je GoodUnsigned
cmp inputLine[bx]
0 ;Input line ends with a zero.
je GoodUnsigned
printf
byte "'%s' is an illegal unsigned integer. "
byte "Please reenter."
cr
lf
0
dword inputLine
jmp InputUnsigned
; Okay
all the characters are cool
let's do the conversion here. Note that
; ES:DI is still pointing at inputLine.
GoodUnsigned: ATOU ;Do the conversion
mov UnsignedInt
ax ;Save the value away.
; Read a hexadecimal value from the user.
InputHex: print
byte "Input a hexadecimal value: "
0
lesi inputLine ;Point es:di at inputLine buffer
gets ;Read a line of text from the user.
; The following code uses the same sneaky trick as the code above.
mov bx
-2
SkipSpcs3: inc bx
cmp inputLine[bx+1]
' ' ;Skip over any spaces.
je SkipSpcs3
TestHex: inc bx ;Move on to next char
mov al
inputLine[bx]
IsXDigit ;See if it's a hex digit.
je TestHex ;Repeat process if it is.
cmp inputLine[bx]
' ' ;See if we end with a
je GoodHex ; reasonable character.
cmp inputLine[bx]
'
'
je GoodHex
cmp inputLine[bx]
0 ;Input line ends with a zero.
je GoodHex
printf
byte "'%s' is an illegal hexadecimal value. "
byte "Please reenter."
cr
lf
0
dword inputLine
jmp InputHex
; Okay
all the characters are cool
let's do the conversion here. Note that
; ES:DI is still pointing at inputLine.
GoodHex: ATOH ;Do the conversion
mov HexValue
ax ;Save the value away.
; Display the results:
printf
byte "Values input:"
cr
lf
byte "Signed: %4d"
cr
lf
byte "Unsigned: %4d"
cr
lf
byte "Hex: %4x"
cr
lf
0
dword SignedInteger
UnsignedInt
HexValue
Quit: ExitPgm
Main endp
cseg ends
sseg segment para stack 'stack'
stk db 1024 dup ("stack ")
sseg ends
zzzzzzseg segment para public 'zzzzzz'
LastBytes db 16 dup (?)
zzzzzzseg ends
end Main
|
Table of Content | |
Chapter Seven: The UCR Standard
Library (Part 2)
26 SEP 1996