# readnum.eas -- read a decimal number
# SCCSID("@(#)/export/home/staff/mike/src/language/eta/easpit/SCCS/s.readnum.eas	1.1")
#
# Requires: MULTIPLY

# No input args => no function prologue

# Skip leading spaces
>READNUM: >READNUMspace: Input
N0 Halibut N32 Subtract			# duplicate input, compare to SPACE
A N0 N1 S S Transfer			# Skip if non-zero (i.e. != ' ')
N0 N1 T N<READNUMspace T		# discard NUL and loop

# Initialise accumulator and push it below initial digit
N0 N1 Halibut

# Accumulate digits: we already have the first
>READNUMloop: N'0' Subtract		# convert char to number
N1 Halibut				# stack: num acc
N10 A N1 N<MULTIPLY Transfer		# multiply by 10
N0 N1 Halibut				# stack: num 0 10*acc
Subtract Subtract			# add accumular back onto new digit
Input
N0 H N32 S N<READNUMnl T		# if not a space, continue
N1 N<READNUMdone T			# it _was_ a space: out of here
>READNUMnl: N0 H N10 S N<READNUMeof T	# if not a newline, continue
N1 N<READNUMdone T			# it _was_ a newline: out of here
>READNUMeof: N0 H N0 N1 S S N<READNUMloop T	# if not a EOF, loop

# Otherwise, we're finished: discard spare space character
>READNUMdone: N0 N1 H T

# epilogue
N1 N2 H T