;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;; EXPRESSION PARSER ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
token_end equ 1
token_reg equ 2
token_hex equ 3
token_add equ 4
token_sub equ 5
token_mul equ 6
token_div equ 7
token_lp equ 8
token_rp equ 9
token_err equ -1
;-----------------------------------------------------------------------------
; Check if byte - some kind of instruction prefix
is_prefix:
cmp al, 0x64 ; fs:
jz .ret
cmp al, 0x65 ; gs:
jz .ret
cmp al, 0x66 ; use16/32
jz .ret
cmp al, 0x67 ; addr16/32
jz .ret
cmp al, 0xF0 ; lock
jz .ret
cmp al, 0xF2 ; repnz
jz .ret
cmp al, 0xF3 ; rep(z)
jz .ret
cmp al, 0x2E ; cs:
jz .ret
cmp al, 0x36 ; ss:
jz .ret
cmp al, 0x3E ; ds:
jz .ret
cmp al, 0x26 ; es:
.ret:
ret
;-----------------------------------------------------------------------------
; Check if byte is hex digit
is_hex_digit:
cmp al, '0'
jb .no
cmp al, '9'
jbe .09
cmp al, 'A'
jb .no
cmp al, 'F'
jbe .AF
cmp al, 'a'
jb .no
cmp al, 'f'
jbe .af
.no:
stc
ret
.09:
sub al, '0'
; clc
ret
.AF:
sub al, 'A'-10
; clc
ret
.af:
sub al, 'a'-10
; clc
ret
;-----------------------------------------------------------------------------
; Find register in the table
find_reg:
mov edi, reg_table
.findreg:
movzx ecx, byte [edi]
stc
jecxz .regnotfound
inc edi
push esi edi ecx
@@:
lodsb
or al, 20h
scasb
loopz @b
pop ecx edi esi
lea edi, [edi+ecx+1]
jnz .findreg
movzx edi, byte [edi-1]
add esi, ecx
.regnotfound:
ret
;-----------------------------------------------------------------------------
; Tokenize expressions
expr_get_token:
lodsb
cmp al, 0
jz .end_token
cmp al, ' '
jbe expr_get_token
cmp al, '+'
jz .add
cmp al, '-'
jz .sub
cmp al, '*'
jz .mul
cmp al, '/'
jz .div
cmp al, '('
jz .lp
cmp al, ')'
jnz .notsign
.rp:
mov al, token_rp
ret
.div:
mov al, token_div
ret
.end_token:
mov al, token_end
ret
.add:
mov al, token_add
ret
.sub:
mov al, token_sub
ret
.mul:
mov al, token_mul
ret
.lp:
mov al, token_lp
ret
.notsign:
dec esi
call find_reg
jc .regnotfound
mov al, token_reg
ret
.regnotfound:
; test for symbol
push esi
@@:
lodsb
cmp al, ' '
ja @b
push eax
mov byte [esi], 0
xchg esi, [esp+4]
call find_symbol_name
mov edi, eax
pop eax
xchg esi, [esp]
mov byte [esi], al
jc @f
add esp, 4
mov al, token_hex
ret
@@:
pop esi
; test for hex number
xor ecx, ecx
xor edi, edi
xor eax, eax
@@:
lodsb
call is_hex_digit
jc @f
shl edi, 4
or edi, eax
inc ecx
jmp @b
@@:
dec esi
jecxz .err
cmp ecx, 8
ja .err
mov al, token_hex
ret
.err:
mov al, token_err
mov esi, aParseError
ret
;-----------------------------------------------------------------------------
expr_read2:
cmp al, token_hex
jz .hex
cmp al, token_reg
jz .reg
cmp al, token_lp
jz .lp
mov al, token_err
mov esi, aParseError
ret
.hex:
mov ebp, edi
.ret:
jmp expr_get_token
.reg:
cmp edi, 24
jz .eip
sub edi, 4
jb .8lo
sub edi, 4
jb .8hi
sub edi, 8
jb .16
mov ebp, [_eax+edi*4]
jmp .ret
.16:
movzx ebp, word [_eax+(edi+8)*4]
jmp .ret
.8lo:
movzx ebp, byte [_eax+(edi+4)*4]
jmp .ret
.8hi:
movzx ebp, byte [_eax+(edi+4)*4+1]
jmp .ret
.eip:
mov ebp, [_eip]
jmp .ret
.lp:
call expr_get_token
call expr_read0
cmp al, token_err
jz @f
cmp al, token_rp
jz expr_get_token
mov al, token_err
mov esi, aParseError
@@:
ret
;-----------------------------------------------------------------------------
expr_read1:
call expr_read2
.1:
cmp al, token_mul
jz .mul
cmp al, token_div
jz .div
ret
.mul:
push ebp
call expr_get_token
call expr_read2
pop edx
; ebp := edx*ebp
imul ebp, edx
jmp .1
.div:
push ebp
call expr_get_token
call expr_read2
pop edx
; ebp := edx/ebp
test ebp, ebp
jz .div0
push eax
xor eax, eax
xchg eax, edx
div ebp
xchg eax, ebp
pop eax
jmp .1
.div0:
mov al, token_err
mov esi, aDivByZero
ret
;-----------------------------------------------------------------------------
expr_read0:
xor ebp, ebp
cmp al, token_add
jz .add
cmp al, token_sub
jz .sub
call expr_read1
.1:
cmp al, token_add
jz .add
cmp al, token_sub
jz .sub
ret
.add:
push ebp
call expr_get_token
call expr_read1
pop edx
; ebp := edx+ebp
add ebp, edx
jmp .1
.sub:
push ebp
call expr_get_token
call expr_read1
pop edx
; ebp := edx-ebp
xchg edx, ebp
sub ebp, edx
jmp .1
;-----------------------------------------------------------------------------
; in: esi->expression
; out: CF=1 if error
; CF=0 and ebp=value if ok
calc_expression:
call expr_get_token
call expr_read0
cmp al, token_end
jz .end
cmp al, token_err
jz @f
mov esi, aParseError
@@:
call put_message
stc
ret
.end:
clc
ret
;-----------------------------------------------------------------------------
get_arg:
lodsb
cmp al, ' '
ja get_arg
mov byte [esi-1], 0
cmp al, 0
jnz .skip_spaces
dec esi
.skip_spaces:
lodsb
cmp al, 0
jz @f
cmp al, ' '
jbe .skip_spaces
@@:
dec esi
ret
; vim: ft=fasm tabstop=4