// #LAYOUT# STD *       #TAKE
// #LAYOUT# *   BASIC_0 #TAKE
// #LAYOUT# *   *       #IGNORE


// Parse a number from the input buffer at (TXTPTR)
// Result is put into FAC1.
// TXTPTR is updated with first position after the number.

// XXX - Remember decimal position and exponent, and apply them
// after to produce normalised floating point number.

// XXX - Does not use routines to access memory under ROMs etc.
// This is important, because this routine operates on numbers in BASIC text.

ij_not_a_digit:
	// XXX check for "." or "E"
	// Other chars terminate the accumulation.

	// Look for exponentiation marker
	// XXX - Implement me!
	// Probably should have a flag so that we know if we are accumulating
	// exponent or mantissa digits
	
	// Look for decimal point
	cmp #$2e
	bne ij_not_decimal
	lda __tokenise_work4
	cmp #$ff
	beq ij_found_decimal
	// More than one decimal point in a number means we have reached the end of the number
	clc
	rts
	
ij_found_decimal:
	// Found decimal.
	// Thus start counting digits after the decimal, so that we
	// can do the necessary number of divide by 10s on the final
	// number.
	lda #$00
	sta __tokenise_work4

	jmp ij_consider_next_digit
	
ij_not_decimal:

	clc
	rts
	
injest_number:
	// Clear FAC1
	jsr erase_fac1

	// Clear decimal position flag
	lda #$ff
	sta __tokenise_work4

	// Check if leading char is a - sign
	// Note: the - will have been tokenised to $AB
	// XXX - implement
	ldy #$00
	lda (TXTPTR),y
	cmp #$AB
	bne ij_loop1 // not minus

	// Set sign to negative
	lda #$ff
	sta FAC1_sign

	// Skip over the minus sign
	jsr consume_character

ij_loop1:
	ldy #$00
	lda (TXTPTR),y
	cmp #$30
	bcc ij_not_a_digit
	cmp #$3a
	bcs ij_not_a_digit

	// It is a digit

	// Only add digit if we have not overflowed the accuracy of
	// the mantissa
	lda FAC1_exponent
	beq ij_accept_precision

	// We have an extra digit after saturating our precision.
	// Thus we should ignore the digit, and just multiply the FAC
	// by 10, but only if we have not seen a decimal point.
	// If we have seen a decimal point, then we can completely ignore
	// the digit, as it is contributing not recordable information

	lda __tokenise_work4
	cmp #$ff
	bne ij_seen_decimal_point
	
	jsr fac1_mul10
	// Fall through
ij_seen_decimal_point:
	jmp ij_consider_next_digit
	
ij_accept_precision:
	// We can accept more precision, so multiply the mantissa by 10, so that
	// we can add the new digit in
	jsr fac1_mul10

	lda FAC1_exponent
	bne ij_consider_next_digit
	
	// Get digit
	ldy #$00
	lda (TXTPTR),y
	sec
	sbc #$30

	// Add to FAC1 mantissa
	clc
	adc FAC1_mantissa+0
	sta FAC1_mantissa+0
	ldx #1
	ldy #3
ij_loop2:	
	lda FAC1_mantissa,x
	adc #$00
	sta FAC1_mantissa,x
	inx
	dey
	bne ij_loop2

	bcc !+
	// Carry set, so we have overflowed.
	// We should shift everything right one digit, and increase
	// the exponent by one.  The non-zero exponent tells us that we
	// can not fit any more precision in.
	jsr fac1_mantissa_div2
!:

ij_consider_next_digit:	
	// Consider next digit
	jsr consume_character
	jmp ij_loop1
	
	rts


erase_fac1:	
	lda #$00
	ldx #8
!:
	sta FAC1_exponent,x
	dex
	bpl !-
	sta FACOV

	rts