expressi.inc

一个用纯汇编 写的操作系统 源代码 是用 TASM 编译器写的

; flat assembler core
; Copyright (c) 1999-2006, Tomasz Grysztar.
; All rights reserved.

convert_expression:
	push	ebp
	call	get_fp_value
	jnc	fp_expression
	mov	[current_offset],esp
      expression_loop:
	push	edi
	mov	edi,single_operand_operators
	call	get_operator
	pop	edi
	or	al,al
	jz	expression_element
	push	eax
	jmp	expression_loop
      expression_element:
	mov	al,[esi]
	cmp	al,1Ah
	je	expression_number
	cmp	al,22h
	je	expression_number
	cmp	al,'('
	je	expression_number
	mov	al,'!'
	stos	byte [edi]
	jmp	expression_operator
      expression_number:
	call	convert_number
      expression_operator:
	push	edi
	mov	edi,operators
	call	get_operator
	pop	edi
	or	al,al
	jz	expression_end
      operators_loop:
	cmp	esp,[current_offset]
	je	push_operator
	mov	bl,al
	and	bl,0F0h
	mov	bh,byte [esp]
	and	bh,0F0h
	cmp	bl,bh
	ja	push_operator
	pop	ebx
	mov	byte [edi],bl
	inc	edi
	jmp	operators_loop
      push_operator:
	push	eax
	jmp	expression_loop
      expression_end:
	cmp	esp,[current_offset]
	je	expression_converted
	pop	eax
	stos	byte [edi]
	jmp	expression_end
      expression_converted:
	pop	ebp
	ret
      fp_expression:
	mov	al,'.'
	stos	byte [edi]
	mov	eax,[fp_value]
	stos	dword [edi]
	mov	eax,[fp_value+4]
	stos	dword [edi]
	mov	eax,[fp_value+8]
	stos	dword [edi]
	pop	ebp
	ret

convert_number:
	lea	eax,[edi-10h]
	cmp	eax,[labels_list]
	jae	out_of_memory
	cmp	byte [esi],'('
	je	expression_value
	inc	edi
	call	get_number
	jc	symbol_value
	or	ebp,ebp
	jz	valid_number
	mov	byte [edi-1],0Fh
	ret
      valid_number:
	cmp	dword [edi+4],0
	jne	qword_number
	cmp	word [edi+2],0
	jne	dword_number
	cmp	byte [edi+1],0
	jne	word_number
      byte_number:
	mov	byte [edi-1],1
	inc	edi
	ret
      qword_number:
	mov	byte [edi-1],8
	add	edi,8
	ret
      dword_number:
	mov	byte [edi-1],4
	scas	dword [edi]
	ret
      word_number:
	mov	byte [edi-1],2
	scas	word [edi]
	ret
      expression_value:
	mov	eax,esp
	sub	eax,100h
	jc	stack_overflow
	cmp	eax,[stack_limit]
	jb	stack_overflow
	inc	esi
	push	[current_offset]
	call	convert_expression
	pop	[current_offset]
	lods	byte [esi]
	cmp	al,')'
	jne	invalid_expression
	ret
      symbol_value:
	push	edi
	mov	edi,address_registers
	call	get_operator
	or	al,al
	jnz	register_value
	mov	edi,directive_operators
	call	get_operator
	pop	edi
	or	al,al
	jnz	broken_value
	lods	byte [esi]
	cmp	al,1Ah
	jne	invalid_value
	lods	byte [esi]
	movzx	ecx,al
	call	get_label_id
      store_label_value:
	mov	byte [edi-1],11h
	stos	dword [edi]
	ret
      broken_value:
	mov	eax,0Fh
	jmp	store_label_value
      register_value:
	pop	edi
	mov	byte [edi-1],10h
	stos	byte [edi]
	ret

get_number:
	xor	ebp,ebp
	lods	byte [esi]
	cmp	al,22h
	je	get_text_number
	cmp	al,1Ah
	jne	not_number
	lods	byte [esi]
	movzx	ecx,al
	mov	[number_start],esi
	mov	al,[esi]
	cmp	al,'$'
	je	number_begin
	sub	al,30h
	cmp	al,9
	ja	invalid_number
      number_begin:
	mov	ebx,esi
	add	esi,ecx
	push	esi
	dec	esi
	mov	dword [edi],0
	mov	dword [edi+4],0
	cmp	byte [ebx],'$'
	je	pascal_hex_number
	cmp	word [ebx],'0x'
	je	get_hex_number
	mov	al,[esi]
	dec	esi
	cmp	al,'h'
	je	get_hex_number
	cmp	al,'b'
	je	get_bin_number
	cmp	al,'d'
	je	get_dec_number
	cmp	al,'o'
	je	get_oct_number
	cmp	al,'H'
	je	get_hex_number
	cmp	al,'B'
	je	get_bin_number
	cmp	al,'D'
	je	get_dec_number
	cmp	al,'O'
	je	get_oct_number
	inc	esi
      get_dec_number:
	mov	ebx,esi
	mov	esi,[number_start]
      get_dec_digit:
	cmp	esi,ebx
	ja	number_ok
	xor	edx,edx
	mov	eax,[edi]
	shld	edx,eax,2
	shl	eax,2
	add	eax,[edi]
	adc	edx,0
	add	eax,eax
	adc	edx,edx
	mov	[edi],eax
	mov	eax,[edi+4]
	add	eax,eax
	jc	dec_out_of_range
	add	eax,eax
	jc	dec_out_of_range
	add	eax,[edi+4]
	jc	dec_out_of_range
	add	eax,eax
	jc	dec_out_of_range
	add	eax,edx
	jc	dec_out_of_range
	mov	[edi+4],eax
	movzx	eax,byte [esi]
	sub	al,30h
	cmp	al,9
	ja	bad_number
	add	[edi],eax
	adc	dword [edi+4],0
	jc	dec_out_of_range
	inc	esi
	jmp	get_dec_digit
      dec_out_of_range:
	or	ebp,-1
	inc	esi
	jmp	get_dec_digit
      bad_number:
	pop	eax
      invalid_number:
	mov	esi,[number_start]
	dec	esi
      not_number:
	dec	esi
	stc
	ret
      get_bin_number:
	xor	bl,bl
      get_bin_digit:
	cmp	esi,[number_start]
	jb	number_ok
	movzx	eax,byte [esi]
	sub	al,30h
	cmp	al,1
	ja	bad_number
	xor	edx,edx
	mov	cl,bl
	dec	esi
	cmp	bl,64
	je	bin_out_of_range
	inc	bl
	cmp	cl,32
	jae	bin_digit_high
	shl	eax,cl
	or	dword [edi],eax
	jmp	get_bin_digit
      bin_digit_high:
	sub	cl,32
	shl	eax,cl
	or	dword [edi+4],eax
	jmp	get_bin_digit
      bin_out_of_range:
	or	al,al
	jz	get_bin_digit
	or	ebp,-1
	jmp	get_bin_digit
      pascal_hex_number:
	cmp	cl,1
	je	bad_number
      get_hex_number:
	xor	bl,bl
      get_hex_digit:
	cmp	esi,[number_start]
	jb	number_ok
	movzx	eax,byte [esi]
	cmp	al,'x'
	je	hex_number_ok
	cmp	al,'$'
	je	pascal_hex_ok
	sub	al,30h
	cmp	al,9
	jbe	hex_digit_ok
	sub	al,7
	cmp	al,15
	jbe	hex_letter_digit_ok
	sub	al,20h
	cmp	al,15
	ja	bad_number
      hex_letter_digit_ok:
	cmp	al,10
	jb	bad_number
      hex_digit_ok:
	xor	edx,edx
	mov	cl,bl
	dec	esi
	cmp	bl,64
	je	hex_out_of_range
	add	bl,4
	cmp	cl,32
	jae	hex_digit_high
	shl	eax,cl
	or	dword [edi],eax
	jmp	get_hex_digit
      hex_digit_high:
	sub	cl,32
	shl	eax,cl
	or	dword [edi+4],eax
	jmp	get_hex_digit
      hex_out_of_range:
	or	al,al
	jz	get_hex_digit
	or	ebp,-1
	jmp	get_hex_digit
      get_oct_number:
	xor	bl,bl
      get_oct_digit:
	cmp	esi,[number_start]
	jb	number_ok
	movzx	eax,byte [esi]
	sub	al,30h
	cmp	al,7
	ja	bad_number
      oct_digit_ok:
	xor	edx,edx
	mov	cl,bl
	dec	esi
	cmp	bl,64
	jae	oct_out_of_range
	add	bl,3
	cmp	cl,30
	je	oct_digit_wrap
	ja	oct_digit_high
	shl	eax,cl
	or	dword [edi],eax
	jmp	get_oct_digit
      oct_digit_wrap:
	shl	eax,cl
	adc	dword [edi+4],0
	or	dword [edi],eax
	jmp	get_oct_digit
      oct_digit_high:
	sub	cl,32
	shl	eax,cl
	or	dword [edi+4],eax
	jmp	get_oct_digit
      oct_out_of_range:
	or	al,al
	jz	get_oct_digit
	or	ebp,-1
	jmp	get_oct_digit
      hex_number_ok:
	dec	esi
      pascal_hex_ok:
	cmp	esi,[number_start]
	jne	bad_number
      number_ok:
	pop	esi
      number_done:
	clc
	ret
      get_text_number:
	lods	dword [esi]
	mov	edx,eax
	xor	bl,bl
	mov	dword [edi],0
	mov	dword [edi+4],0
      get_text_character:
	sub	edx,1
	jc	number_done
	movzx	eax,byte [esi]
	inc	esi
	mov	cl,bl
	cmp	bl,64
	je	text_out_of_range
	add	bl,8
	cmp	cl,32
	jae	text_character_high
	shl	eax,cl
	or	dword [edi],eax
	jmp	get_text_character
      text_character_high:
	sub	cl,32
	shl	eax,cl
	or	dword [edi+4],eax
	jmp	get_text_character
      text_out_of_range:
	or	ebp,-1
	jmp	get_text_character

get_fp_value:
	push	edi esi
	lods	byte [esi]
	cmp	al,1Ah
	je	fp_value_start
	cmp	al,'-'
	je	fp_sign_ok
	cmp	al,'+'
	jne	not_fp_value
      fp_sign_ok:
	lods	byte [esi]
	cmp	al,1Ah
	jne	not_fp_value
      fp_value_start:
	lods	byte [esi]
	movzx	ecx,al
	cmp	cl,1
	jbe	not_fp_value
	lea	edx,[esi+1]
	xor	ah,ah
      check_fp_value:
	lods	byte [esi]
	cmp	al,'.'
	je	fp_character_dot
	cmp	al,'E'
	je	fp_character_exp
	cmp	al,'e'
	je	fp_character_exp
	cmp	al,'F'
	je	fp_last_character
	cmp	al,'f'
	je	fp_last_character
      digit_expected:
	cmp	al,'0'
	jb	not_fp_value
	cmp	al,'9'
	ja	not_fp_value
	jmp	fp_character_ok
      fp_character_dot:
	cmp	esi,edx
	je	not_fp_value
	or	ah,ah
	jnz	not_fp_value
	or	ah,1
	lods	byte [esi]
	loop	digit_expected
      not_fp_value:
	pop	esi edi
	stc
	ret
      fp_last_character:
	cmp	cl,1
	jne	not_fp_value
	or	ah,4
	jmp	fp_character_ok
      fp_character_exp:
	cmp	esi,edx
	je	not_fp_value
	cmp	ah,1
	ja	not_fp_value
	or	ah,2
	cmp	ecx,1
	jne	fp_character_ok
	cmp	byte [esi],'+'
	je	fp_exp_sign
	cmp	byte [esi],'-'
	jne	fp_character_ok
      fp_exp_sign:
	inc	esi
	cmp	byte [esi],1Ah
	jne	not_fp_value
	inc	esi
	lods	byte [esi]
	movzx	ecx,al
	inc	ecx
      fp_character_ok:
	dec	ecx
	jnz	check_fp_value
	or	ah,ah
	jz	not_fp_value
	pop	esi
	lods	byte [esi]
	mov	[fp_sign],0
	cmp	al,1Ah
	je	fp_get
	inc	esi
	cmp	al,'+'
	je	fp_get
	mov	[fp_sign],1
      fp_get:
	lods	byte [esi]
	movzx	ecx,al
	xor	edx,edx
	mov	edi,fp_value
	mov	[edi],edx
	mov	[edi+4],edx
	mov	[edi+12],edx
	call	fp_optimize
	mov	[fp_format],0
	mov	al,[esi]
      fp_before_dot:
	lods	byte [esi]
	cmp	al,'.'
	je	fp_dot
	cmp	al,'E'
	je	fp_exponent
	cmp	al,'e'
	je	fp_exponent
	cmp	al,'F'
	je	fp_done
	cmp	al,'f'
	je	fp_done
	sub	al,30h
	mov	edi,fp_value+16
	xor	edx,edx
	mov	dword [edi+12],edx
	mov	dword [edi],edx
	mov	dword [edi+4],edx
	mov	[edi+7],al
	mov	dl,7
	mov	dword [edi+8],edx
	call	fp_optimize
	mov	edi,fp_value
	push	ecx
	mov	ecx,10
	call	fp_mul
	pop	ecx
	mov	ebx,fp_value+16
	call	fp_add
	loop	fp_before_dot
      fp_dot:
	mov	edi,fp_value+16
	xor	edx,edx
	mov	[edi],edx
	mov	[edi+4],edx
	mov	byte [edi+7],80h
	mov	[edi+8],edx
	mov	dword [edi+12],edx
	dec	ecx
	jz	fp_done
      fp_after_dot:
	lods	byte [esi]
	cmp	al,'E'
	je	fp_exponent
	cmp	al,'e'
	je	fp_exponent
	cmp	al,'F'
	je	fp_done
	cmp	al,'f'
	je	fp_done
	inc	[fp_format]
	cmp	[fp_format],80h
	jne	fp_counter_ok
	mov	[fp_format],7Fh
      fp_counter_ok:
	dec	esi
	mov	edi,fp_value+16
	push	ecx
	mov	ecx,10
	call	fp_div
	push	dword [edi]
	push	dword [edi+4]
	push	dword [edi+8]
	push	dword [edi+12]
	lods	byte [esi]
	sub	al,30h
	movzx	ecx,al
	call	fp_mul
	mov	ebx,edi
	mov	edi,fp_value
	call	fp_add
	mov	edi,fp_value+16
	pop	dword [edi+12]
	pop	dword [edi+8]
	pop	dword [edi+4]
	pop	dword [edi]
	pop	ecx
	loop	fp_after_dot
	jmp	fp_done
      fp_exponent:
	or	[fp_format],80h
	xor	edx,edx
	xor	ebp,ebp
	dec	ecx
	jnz	get_exponent
	cmp	byte [esi],'+'
	je	fp_exponent_sign
	cmp	byte [esi],'-'
	jne	fp_done
	not	ebp
      fp_exponent_sign:
	add	esi,2
	lods	byte [esi]
	movzx	ecx,al
      get_exponent:
	movzx	eax,byte [esi]
	inc	esi
	sub	al,30h
	cmp	al,10
	jae	exponent_ok
	imul	edx,10
	cmp	edx,8000h
	jae	value_out_of_range
	add	edx,eax
	loop	get_exponent
      exponent_ok:
	mov	edi,fp_value
	or	edx,edx
	jz	fp_done
	mov	ecx,edx
	or	ebp,ebp
	jnz	fp_negative_power
      fp_power:
	push	ecx
	mov	ecx,10
	call	fp_mul
	pop	ecx
	loop	fp_power
	jmp	fp_done
      fp_negative_power:
	push	ecx
	mov	ecx,10
	call	fp_div
	pop	ecx
	loop	fp_negative_power
      fp_done:
	mov	edi,fp_value
	mov	al,[fp_format]
	mov	[edi+10],al
	mov	al,[fp_sign]
	mov	[edi+11],al
	test	byte [edi+15],80h
	jz	fp_ok
	add	dword [edi],1
	adc	dword [edi+4],0
	jnc	fp_ok
	mov	eax,[edi+4]
	shrd	[edi],eax,1
	shr	eax,1
	or	eax,80000000h
	mov	[edi+4],eax
	inc	word [edi+8]
      fp_ok:
	pop	edi
	clc
	ret
      fp_mul:
	or	ecx,ecx
	jz	fp_zero
	mov	eax,[edi+12]
	mul	ecx
	mov	[edi+12],eax
	mov	ebx,edx
	mov	eax,[edi]
	mul	ecx
	add	eax,ebx
	adc	edx,0
	mov	[edi],eax
	mov	ebx,edx
	mov	eax,[edi+4]
	mul	ecx
	add	eax,ebx
	adc	edx,0
	mov	[edi+4],eax
      .loop:
	or	edx,edx
	jz	.done
	mov	eax,[edi]
	shrd	[edi+12],eax,1
	mov	eax,[edi+4]
	shrd	[edi],eax,1
	shrd	eax,edx,1
	mov	[edi+4],eax
	shr	edx,1
	inc	dword [edi+8]
	cmp	dword [edi+8],8000h
	jge	value_out_of_range
	jmp	.loop
      .done: