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EttinOS
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Rework cursor positioning after input.

This commit is contained in:
CrazyEttin 2021-06-04 20:36:46 +03:00
parent 522905d77c
commit 9582045822
3 changed files with 163 additions and 173 deletions
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175
source/readln.inc
View File

@ -2,181 +2,10 @@
readln:
;Store the input length in the stack
mov ah, 0
push ax
;Read the string
call readstr
;Initialise the destination with spaces
mov cx, ax
mov al, 0x20
rep stosb
pop ax
push ax
sub di, ax
;Initialise the cursor pointer
mov bl, 0x1
;Initialise the last input line pointer
mov ah, 0x3
int 0x10
mov byte [.lastln], dh
.loop:
;Read a keypress
mov ah, 0x0
int 0x16
;Check for return
cmp al, 0xd
je .return
;Check for backspace
cmp al, 0x8
je .backspace
;Check for input end
pop dx
push dx
cmp bl, dl
je .loop
;Check for space
cmp al, 0x20
je .space
;Check for erase
cmp al, 0x9
je .erase
;Check for non-printing characters
cmp al, 0x1f
jle .loop
cmp al, 0x7f
je .loop
.char:
;Store the character
stosb
;Print the character
mov ah, 0xe
int 0x10
;Move the cursor pointer
inc bl
call .checkln
jmp .loop
.erase:
;Replace the cursor position with a space
mov al, 0x20
jmp .char
.space:
call .nextchar
jmp .loop
.backspace:
;Check for the input beginning
cmp bl, 0x1
je .loop
call .prevchar
jmp .loop
.return:
;Go to the end of the input
mov bh, 0x0
sub di, bx
pop ax
add di, ax
.findtrailing:
;Check for a trailing space
cmp byte [di], 0x20
je .deltrailing
jmp .done
.deltrailing:
;Delete a trailing space
mov al, 0x0
stosb
sub di, 0x2
jmp .findtrailing
.done:
;Move the cursor to the last line of input
mov ah, 0x2
mov dh, [.lastln]
int 0x10
;Print a newline
call newline
ret
.lastln:
db 0x0
.nextchar:
;Get the cursor position
mov ah, 0x3
int 0x10
;Move from the end of a line to the beginning of the next one
cmp dl, [cpl]
je .nextln
;Move forward within a line
inc dl
mov ah, 0x2
int 0x10
inc di
inc bl
ret
.nextln:
mov ah, 0x2
inc dh
mov dl, 0x1
int 0x10
inc di
inc bl
;Go to the last input line check
call .checkln
ret
.prevchar:
;Get the cursor position
mov ah, 0x3
int 0x10
;Move from the beginning of a line to the end of the previous one
cmp dl, 0x1
je .prevln
;Move backward within a line
dec dl
mov ah, 0x2
int 0x10
dec di
dec bl
ret
.prevln:
mov ah, 0x2
dec dh
mov dl, [cpl]
int 0x10
dec di
dec bl
ret
.checkln:
;Get the cursor position
mov ah, 0x3
int 0x10
;Check if the current line is the last one of the input
cmp dh, [.lastln]
jg .markln
ret
.markln:
;Mark the current line as the last one of the input
mov byte [.lastln], dh
ret

160
source/readstr.inc Normal file
View File

@ -0,0 +1,160 @@
;Reads a string of at most al characters to di until a return.
readstr:
;Store the input length in the stack
mov ah, 0
push ax
;Initialise the destination with spaces
mov cx, ax
mov al, 0x20
rep stosb
pop ax
push ax
sub di, ax
;Initialise the cursor pointer
mov bl, 0x1
.loop:
;Read a keypress
mov ah, 0x0
int 0x16
;Check for return
cmp al, 0xd
je .return
;Check for backspace
cmp al, 0x8
je .backspace
;Check for input end
pop dx
push dx
cmp bl, dl
je .loop
;Check for space
cmp al, 0x20
je .space
;Check for erase
cmp al, 0x9
je .erase
;Check for non-printing characters
cmp al, 0x1f
jle .loop
cmp al, 0x7f
je .loop
.char:
;Store the character
stosb
;Print the character
mov ah, 0xe
int 0x10
;Move the cursor pointer
inc bl
jmp .loop
.erase:
;Replace the cursor position with a space
mov al, 0x20
jmp .char
.space:
call .nextchar
inc di
inc bl
jmp .loop
.backspace:
;Check for the input beginning
cmp bl, 0x1
je .loop
call .prevchar
dec di
dec bl
jmp .loop
.return:
;Go to the end of the input
pop ax
mov bh, 0x0
sub ax, bx
push di
add di, ax
.findtrailing:
;Check for a trailing space
cmp byte [di], 0x20
je .deltrailing
jmp .end
.deltrailing:
;Delete a trailing space
mov al, 0x0
stosb
sub di, 0x2
jmp .findtrailing
.end:
;Move the cursor to the end of the input string
pop di
.findend:
cmp byte [di], 0x0
jne .notend
jmp .done
.notend:
call .nextchar
inc di
inc bl
jmp .findend
.done:
ret
.nextchar:
;Get the cursor position
mov ah, 0x3
int 0x10
;Move from the end of a line to the beginning of the next one
cmp dl, [cpl]
je .nextln
;Move forward within a line
inc dl
mov ah, 0x2
int 0x10
ret
.nextln:
mov ah, 0x2
inc dh
mov dl, 0x1
int 0x10
ret
.prevchar:
;Get the cursor position
mov ah, 0x3
int 0x10
;Move from the beginning of a line to the end of the previous one
cmp dl, 0x1
je .prevln
;Move backward within a line
dec dl
mov ah, 0x2
int 0x10
ret
.prevln:
mov ah, 0x2
dec dh
mov dl, [cpl]
int 0x10
ret

1
source/system.asm
View File

@ -4,6 +4,7 @@ jmp start
;Calls
%include "printstr.inc"
%include "println.inc"
%include "readstr.inc"
%include "readln.inc"
%include "newline.inc"
%include "cmpstr.inc"