more sane directory name, updated binaries

src/basic/injest_number.s

@@ -0,0 +1,156 @@
+// #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