util.m

compiler-compiler. This is a compiler-compiler with table-driven scanner, table-driven parser.

%
%--------------------------------------------------------------%
% gtstr                                                        %
%--------------------------------------------------------------%
% Check if string1 > string2.
% Entry : address of string1 -> r1
%         address of string2 -> r2
% Exit : r1 = 1 (true)
%        r1 = 0 (false)
%
gtstr	align
	add	r3,r0,r0		% Initialize r3 (r3 = 0)
	add	r4,r0,r0		% Initialize r4 (r4 = 0)
gtstr1	lb	r3,0(r1)		% Load ch1 from 1st string
	lb	r4,0(r2)		% Load ch2 from 2nd string
	cgt	r5,r3,r4		% ch1 > ch2 ?
	bnz	r5,gtstr3		% Branch if true
	clt	r5,r3,r4		% ch1 < ch2 ?
	bnz	r5,gtstr2		% Branch if true
	ceq	r5,r3,r0		% ch1 = '\0' ?
	bnz	r5,gtstr2		% Branch if true
	addi	r1,r1,1			% i++
	addi	r2,r2,1			% j++
	j	gtstr1			% Loop if not finished
gtstr2	add	r1,r0,r0		% Return false
	j	gtstr4
gtstr3	addi	r1,r0,1			% Return true
gtstr4	jr	r15			% Return to the caller
	align
%
%
%--------------------------------------------------------------%
% gtestr                                                       %
%--------------------------------------------------------------%
% Check if string1 >= string2.
% Entry : address of string1 -> r1
%         address of string2 -> r2
% Exit : r1 = 1 (true)
%        r1 = 0 (false)
%
gtestr	align
	add	r3,r0,r0		% Initialize r3 (r3 = 0)
	add	r4,r0,r0		% Initialize r4 (r4 = 0)
gtestr1	lb	r3,0(r1)		% Load ch1 from 1st string
	lb	r4,0(r2)		% Load ch2 from 2nd string
	cgt	r5,r3,r4		% ch1 > ch2 ?
	bnz	r5,gtestr3		% Branch if true
	clt	r5,r3,r4		% ch1 < ch2 ?
	bnz	r5,gtestr2		% Branch if true
	ceq	r5,r3,r0		% ch1 = '\0' ?
	bnz	r5,gtestr3		% Branch if true
	addi	r1,r1,1			% i++
	addi	r2,r2,1			% j++
	j	gtestr1			% Loop if not finished
gtestr2	add	r1,r0,r0		% Return false
	j	gtestr4
gtestr3	addi	r1,r0,1			% Return true
gtestr4	jr	r15			% Return to the caller
	align
%
%
%--------------------------------------------------------------%
% ltstr                                                        %
%--------------------------------------------------------------%
% Check if string1 < string2.
% Entry : address of string1 -> r1
%         address of string2 -> r2
% Exit : r1 = 1 (true)
%        r1 = 0 (false)
%
ltstr	align
	add	r3,r0,r0		% Initialize r3 (r3 = 0)
	add	r4,r0,r0		% Initialize r4 (r4 = 0)
ltstr1	lb	r3,0(r1)		% Load ch1 from 1st string
	lb	r4,0(r2)		% Load ch2 from 2nd string
	clt	r5,r3,r4		% ch1 < ch2 ?
	bnz	r5,ltstr3		% Branch if true
	cgt	r5,r3,r4		% ch1 > ch2 ?
	bnz	r5,ltstr2		% Branch if true
	ceq	r5,r3,r0		% ch1 = '\0' ?
	bnz	r5,ltstr2		% Branch if true
	addi	r1,r1,1			% i++
	addi	r2,r2,1			% j++
	j	ltstr1			% Loop if not finished
ltstr2	add	r1,r0,r0		% Return false
	j	ltstr4
ltstr3	addi	r1,r0,1			% Return true
ltstr4	jr	r15			% Return to the caller
	align
%
%
%--------------------------------------------------------------%
% ltestr                                                       %
%--------------------------------------------------------------%
% Check if string1 <= string2.
% Entry : address of string1 -> r1
%         address of string2 -> r2
% Exit : r1 = 1 (true)
%        r1 = 0 (false)
%
ltestr	align
	add	r3,r0,r0		% Initialize r3 (r3 = 0)
	add	r4,r0,r0		% Initialize r4 (r4 = 0)
ltestr1	lb	r3,0(r1)		% Load ch1 from 1st string
	lb	r4,0(r2)		% Load ch2 from 2nd string
	clt	r5,r3,r4		% ch1 < ch2 ?
	bnz	r5,ltestr3		% Branch if true
	cgt	r5,r3,r4		% ch1 > ch2 ?
	bnz	r5,ltestr2		% Branch if true
	ceq	r5,r3,r0		% ch1 = '\0' ?
	bnz	r5,ltestr3		% Branch if true
	addi	r1,r1,1			% i++
	addi	r2,r2,1			% j++
	j	ltestr1			% Loop if not finished
ltestr2	add	r1,r0,r0		% Return false
	j	ltestr4
ltestr3	addi	r1,r0,1			% Return true
ltestr4	jr	r15			% Return to the caller
	align
%
%
%--------------------------------------------------------------%
% lenstr                                                       %
%--------------------------------------------------------------%
% Returns length of string. '\n' is concidered one char.
% Entry : address of string -> -8(r14)
% Exit : result -> -12(r14)
%
lenstr	align
	sw	-4(r14),r15		% Store link in stack
	sw	-16(r14),r1		% Save registers' old values on stack
	sw	-20(r14),r2
	sw	-24(r14),r3
	sw	-28(r14),r4
	lw	r1,-8(r14)		% Retrieve argument from stack
	add	r2,r0,r0		% Initialize length counter (len = 0)
	add	r3,r0,r0		% Initialize ch holder (r3 = 0)
lenstr1	lb	r3,0(r1)		% Load ch from string
	ceq	r4,r3,r0		% ch = '\0' ?
	bnz	r4,lenstr2		% Branch if true
	addi	r1,r1,1			% i++
	ceqi	r4,r3,13		% ch = LF ?
	bnz	r4,lenstr1		% Skip ch and loop
	addi	r2,r2,1			% len++
	j	lenstr1			% Loop if not finished
lenstr2	add	r1,r0,r2		% Return length of the string
	sw	-12(r14),r1		% Save result on stack
	lw	r1,-16(r14)		% Reset registers to their old values
	lw	r2,-20(r14)
	lw	r3,-24(r14)
	lw	r4,-28(r14)
	lw	r15,-4(r14)		% Load link from stack
	jr	r15			% Return to the caller
	align
%
%
%--------------------------------------------------------------%
% ordstr                                                       %
%--------------------------------------------------------------%
% Returns ASCII number of the 1st char of a string.
% Entry : address of string -> -8(r14)
% Exit : result -> -12(r14)
%
ordstr	align
	sw	-4(r14),r15		% Store link in stack
	sw	-16(r14),r1		% Save registers' old values on stack
	sw	-20(r14),r2
	lw	r1,-8(r14)		% Retrieve argument from stack
	add	r2,r0,r0		% Initialize ch holder (r2 = 0)
	lb	r2,0(r1)		% Load ch from string
	add	r1,r0,r2		% Return ascii code of ch
	sw	-12(r14),r1		% Save result on stack
	lw	r1,-16(r14)		% Reset registers to their old values
	lw	r2,-20(r14)
	lw	r15,-4(r14)		% Load link from stack
	jr	r15			% Return to the caller
	align
%
%
%--------------------------------------------------------------%
% substr                                                       %
%--------------------------------------------------------------%
% Returns the start & end pos. of a substring. '\n' is concidered
% one char. Returns empty string in case of illegal start and/or
% substring pos.
% Entry : address of string -> -8(r14)
%         substring start pos. -> -12(r14)
%         substring end pos. -> -16(r14)
% Exit : address of substring start pos. -> -20(r14)
%        address of substring end pos. -> -24(r14)
%
substr	align
	sw	-4(r14),r15		% Store link in stack
	sw	-28(r14),r1		% Save registers' old values on stack
	sw	-32(r14),r2
	sw	-36(r14),r3
	sw	-40(r14),r4
	sw	-44(r14),r5
	sw	-48(r14),r6
	lw	r1,-8(r14)		% Retrieve arguments from stack
	lw	r2,-12(r14)
	lw	r3,-16(r14)
	add	r5,r0,r0		% Initialize copy reg (r5 = 0)
	cle	r4,r2,r0		% N < 0 ?
	bnz	r4,substr4		% Branch if true
	cle	r4,r2,r3		% M <= N ?
	bz	r4,substr4		% Branch if true
	add	r2,r2,r1		% Start pos. of the substr. in memory
	subi	r2,r2,1
	add	r3,r3,r1		% End pos. of substr. in memory
	subi	r3,r3,1
substr1	lb	r5,0(r1)		% Load ch in copy register starting from ch1
	ceq	r6,r5,r0		% ch = '\0' ?
	bnz	r6,substr4		% Branch if true
	ceq	r4,r2,r1		% Current pos. = Start pos. ?
	bnz	r4,substr2		% Branch if true
	ceqi	r6,r5,13		% ch = LF ?
	bz	r6,substr6		% Branch if false
	addi	r2,r2,1			% Move start pos
	addi	r3,r3,1			% Move end pos
substr6	addi	r1,r1,1			% Move current pos.
	j	substr1			% Loop if current pos. != start pos.
substr2	lb	r5,0(r2)		% Load ch in copy register starting from star pos.
	ceq	r6,r5,r0		% ch = '\0' ?
	bnz	r6,substr4		% Branch if true
	ceqi	r6,r5,13		% ch = LF ?
	bz	r6,substr7		% Branch if false
	addi	r3,r3,1			% Move end pos
substr7	ceq	r4,r3,r2		% Current pos. = end pos. ?
	bnz	r4,substr3		% Branch if true
	addi	r2,r2,1			% Move current pos.
	j	substr2			% Loop if current pos. != end pos.
substr3	lb	r5,0(r3)		% Load ch of end pos. in copy register
	ceq	r6,r5,r0		% ch = '\0' ?
	bnz	r6,substr4		% Branch if true
	j	substr5
substr4	addi	r1,r0,EMPTY		% Start & end pos. pointing to ""
	addi	r3,r0,EMPTY
substr5	sw	-20(r14),r1		% Store results on stack
	sw	-24(r14),r3
	lw	r1,-28(r14)		% Reset regiters to old values
	lw	r2,-32(r14)
	lw	r3,-36(r14)
	lw	r4,-40(r14)
	lw	r5,-44(r14)
	lw	r6,-48(r14)
	lw	r15,-4(r14)		% Load link from stack
	jr	r15			% Return to caller
	align
EMPTY	db	0			% Empty string
	align
%
%
%-------------------------  End of file -----------------------%