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numbers to literals #24

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numbers to literals #24

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17 changes: 9 additions & 8 deletions sectorc.s
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@
%define TOK_GT 14
%define TOK_LE 133
%define TOK_GE 153
%define TOK_END_COMMENT 65475

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Common register uses
Expand Down Expand Up @@ -321,24 +322,24 @@ tok_next2:
;; [fall-through]
tok_next:
call getch
cmp al,32 ; skip spaces (anything <= ' ' is considered space)
cmp al,' ' ; skip spaces (anything <= ' ' is considered space)
jle tok_next

xor bx,bx ; zero token reg
xor cx,cx ; zero last-two chars reg

cmp al,57
cmp al,'9'
setle dl ; tok_is_num = (al <= '9')

_nextch:
cmp al,32
cmp al,' '
jle _done ; if char is space then break

shl cx,8
mov cl,al ; shift this char into cx

imul bx,10
sub ax,48
sub ax,'0'
add bx,ax ; atoi computation: bx = 10 * bx + (ax - '0')

call getch
Expand All @@ -358,13 +359,13 @@ _done:

_comment_double_slash:
call getch ; get next char
cmp al,10 ; check for newline '\n'
cmp al,`\n` ; check for newline '\n'
jne _comment_double_slash ; [loop]
jmp tok_next ; [tail-call]

_comment_multi_line:
call tok_next ; get next token
cmp ax,65475 ; check for token "*/"
cmp ax,TOK_END_COMMENT ; check for token "*/"
jne _comment_multi_line ; [loop]
jmp tok_next ; [tail-call]

Expand All @@ -376,7 +377,7 @@ getch:
xor si,si ; use ds:0 as a semi-colon buffer, encodes smaller via si
mov ax,[si] ; load the semi-colon buffer
xor [si],ax ; zero the buffer
cmp al,59 ; check for ';'
cmp al,';' ; check for ';'
je getch_done ; if ';' return it

getch_tryagain:
Expand All @@ -387,7 +388,7 @@ getch_tryagain:
and ah,0x80 ; check for failure and clear ah as a side-effect
jne getch_tryagain ; failed, try again later

cmp al,59 ; check for ';'
cmp al,';' ; check for ';'
jne getch_done ; if not ';' return it
mov [si],ax ; save the ';'
xor ax,ax ; return 0 instead, treated as whitespcae
Expand Down