2020/day3: part1 and part2

.gitignore

@@ -2,3 +2,4 @@
 *.o
 *.bin
 *.d
+*.map

2019/day1/part1_part2.s

@@ -50,7 +50,7 @@ end:	.long _binary_2019_day1_input_txt_end
 	.global _parse_int
 	.align 4
 _parse_int:
-	/* r0 = pointer to text ; r1 = number */
+	/* r8 = pointer to text ; r1 = number */
 	mov	#0,r1	/* r1: accumulated number */
 parse_int_loop:
 	mov.b 	@r8+,r2

2019/deps.mk

@@ -1,2 +1,2 @@
-2019/day1/part1.elf: 2019/day1/part1_part2.o 2019/day1/sample.txt.o 2019/day1/input.txt.o
+2019/day1/part1_part2.elf: 2019/day1/part1_part2.o 2019/day1/sample.txt.o 2019/day1/input.txt.o
 	$(DEFAULT_LINK)

2020/day2/sample.txt

@@ -0,0 +1,3 @@
+1-3 a: abcde
+1-3 b: cdefg
+2-9 c: ccccccccc

2020/day2/solution.s

@@ -0,0 +1,134 @@
+	.global _start
+_start:
+	mova	stack_top,r0
+	mov	r0,r15
+
+	/* part1 */
+	mova	_part1,r0
+	mov 	r0,r14
+	mova	solve,r0
+	jsr	@r0
+	nop
+	/* move part1 answer to GBR */
+	ldc	r13,gbr
+
+	/* part2 */
+	mova	_part2,r0
+	mov 	r0,r14
+	mova	solve,r0
+	jsr	@r0
+	nop
+	/* move part2 answer to VBR */
+	ldc	r13,vbr
+
+	trapa	#0
+
+	/* return number of valid passwords in r13 */
+	.balign 4
+solve:
+	sts.l	pr,@-r15
+
+	mov.l	start,r8
+	mov.l	end,r9
+
+	/* password is from r1 to r8, excluding r8; next line is at r8 */
+	mov	#0,r13
+line_loop:
+	mova	_parse_line,r0
+	jsr	@r0
+	nop
+	jsr	@r14
+	nop
+	cmp/eq	r8,r9
+	bf/s	line_loop
+	add	r1,r13
+
+	lds.l	@r15+,pr
+	rts
+	nop
+
+	/* return: valid as `1` in r1 */
+	/* r10: test position 1 */
+	/* r11: test position 2 */
+	/* r12: test character */
+	.balign 4
+_part2:
+	add	#-1,r1		/* offset for 1-based indexing */
+	mov	r10,r0
+	mov.b 	@(r0,r1),r3	/* r3: character */
+	cmp/eq	r3,r12
+	movt	r2
+	mov	r11,r0
+	mov.b 	@(r0,r1),r3	/* r3: character */
+	cmp/eq	r3,r12
+	movt	r1
+	rts
+	xor	r2,r1
+
+	/* return: valid as `1` in r1 */
+	/* r10: count >= lower bound */
+	/* r11: count <= upper bound */
+	/* r12: test character */
+	.balign 4
+_part1:
+	mov	#0,r2 		/* r2: count */
+part1_loop:
+	cmp/eq	r1,r8
+	bt	part1_break
+	mov.b	@r1+,r3		/* r3: character */
+	cmp/eq	r3,r12
+	movt	r0
+	bra	part1_loop
+	add	r0,r2
+part1_break:
+	/* lower bound */
+	cmp/hs	r10,r2		/* Rn ≥ Rm (unsigned) ; r2 >= r10 */
+	movt	r0
+	cmp/hs	r2,r11		/* Rn ≥ Rm (unsigned) ; r11 >= r2 */
+	movt	r1
+	rts
+	and	r0,r1
+
+	.balign 4
+_parse_line:
+	/* save PR */
+	sts.l	pr,@-r15
+
+	mov.l	parse_base10_ptr,r0
+	jsr	@r0
+	nop
+	mov	r1,r10 		/* r10: first number */
+	mov.l	parse_base10_ptr,r0
+	jsr	@r0
+	nop
+	mov	r1,r11 		/* r11: second number */
+
+	mov.b	@r8+,r12 	/* r12: character */
+	/* skip colon character ; skip space character */
+	add	#2,r8
+	/* advance until newline */
+	mov	r8,r1
+newline_loop:
+	mov.b	@r8+,r0
+	cmp/eq	#0xa,r0
+	bf	newline_loop
+
+	/* restore PR */
+	lds.l	@r15+,pr
+	rts
+	nop
+
+	.balign 4
+parse_base10_ptr: /* r8 = pointer to text ; r1 = returned number */
+	.long	_parse_base10
+
+	.balign 4
+start:	.long _binary_2020_day2_input_txt_start
+end:	.long _binary_2020_day2_input_txt_end
+
+	.balign 4
+stack_bot:
+	.rept 16
+	.long 0
+	.endr
+stack_top:

2020/day3/input.txt

@@ -0,0 +1,323 @@
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2020/day3/sample.txt

@@ -0,0 +1,11 @@
+..##.......
+#...#...#..
+.#....#..#.
+..#.#...#.#
+.#...##..#.
+..#.##.....
+.#.#.#....#
+.#........#
+#.##...#...
+#...##....#
+.#..#...#.#

2020/day3/solution.s

@@ -0,0 +1,161 @@
+	.global _start
+_start:
+	mova	stack_top,r0
+	mov	r0,r15
+
+_input:
+	mov.l	start,r8
+	mov.l	size,r9
+
+	/* returns stride in r1 */
+	mova	_calculate_stride,r0
+	jsr	@r0
+	mov	r8,r1
+
+	mov	r1,r10		/* r10: stride */
+
+	/* part 1 */
+	mov	#3,r13		/* right 3 */
+	mov	#1,r14		/* down 1 */
+
+	mova	_solve,r0
+	jsr	@r0
+	nop
+
+	ldc	r7,gbr		/* part1 answer */
+
+	/* part 2 */
+	mova	part2_data,r0
+	mov	r0,r4		/* r4: part2 data start */
+	mov	#10,r3
+	add	r4,r3		/* r3: part2 data end */
+
+	mov	#1,r6		/* r6: tree multiplier */
+
+part2_loop:
+	mov.b	@r4+,r13	/* right */
+	mov.b	@r4+,r14	/* down */
+
+	mova	_solve,r0
+	jsr	@r0
+	nop
+
+	dmulu.l	r7,r6
+	cmp/eq	r4,r3
+	bf/s	part2_loop
+	sts	macl,r6
+
+	/* part2 answer : mach,macl */
+
+	trapa	#0
+
+	/* right, down */
+	.balign 4
+part2_data:
+	.byte 1, 1
+	.byte 3, 1
+	.byte 5, 1
+	.byte 7, 1
+	.byte 1, 2
+
+	/* r7: number of trees (in/out) */
+	.balign 4
+_solve:
+	/* initial state */
+	mov	#0,r7		/* number of trees encountered */
+	mov	#0,r11		/* position X */
+	mov	#0,r12		/* position Y */
+solve_loop:
+	/* return value in r1 */
+	sts.l	pr,@-r15
+	mova	_slope_step,r0
+	jsr	@r0
+	nop
+	lds.l	@r15+,pr
+
+	cmp/pz	r1		/* r1 ≥ 0 */
+	bf	solve_end	/* this is the end */
+	bra	solve_loop
+	add	r1,r7		/* increment tree count */
+
+solve_end:
+	rts
+	nop
+
+	.balign 4
+_slope_step:
+	/* r11: position X */
+	/* r12: position Y */
+	/* r13: right N    */
+	/* r14: down N     */
+	/* r8 : start      */
+	/* r9 : size       */
+	/* r10: stride     */
+	/* return r1 : tree encountered (-1,0,1) */
+
+	add 	r13,r11		/* r11 + r13 → r11 (X) */
+	add 	r14,r12		/* r12 + r14 → r12 (Y) */
+
+	/* Y-coordinate × stride → r5 */
+	mulu.w	r10,r12		/* offset */
+	sts	macl,r5
+
+	sts.l	pr,@-r15
+
+	/* X-axis wrap-around */
+	mov	r11,r1
+	mov	r10,r0
+	add	#-1,r0		/* subtract 1 to remove newline */
+	mov.l	div32_16_ptr,r2
+	jsr	@r2		/* r1 ÷ r0 → r1 ; (clobbers r0,r1) */
+	mov	r0,r2		/* save width in r2 (not clobbered) */
+
+	lds.l	@r15+,pr
+
+	/* recover the modulus with a multiplication + subtraction */
+	mulu.w	r2,r1
+	sts	macl,r1
+	mov	r11,r0
+	sub	r1,r0		/* r0 - r1 → r0
+
+	/* calculate offset (y_off + x_off → off) */
+	add	r5,r0
+	/* compare r0 offset with r9 size */
+	cmp/hs	r9,r0		/* r0 ≥ r9 → T */
+	bt	end_of_slope
+
+	/* get tree */
+	mov.b	@(r0,r8),r0
+	cmp/eq	#0x23,r0	/* 0x23 ascii `#` */
+	rts
+	movt	r1
+end_of_slope:
+	rts
+	mov	#-1,r1		/* -1: end of slope */
+
+	.balign 4
+div32_16_ptr:	.long _div32_16
+
+	.balign 4
+_calculate_stride:
+	/* r8: const input start                   */
+	/* r1: input start (initialized by caller) */
+	/* return r1 : stride */
+loop:
+	mov.b	@r1+,r0
+	cmp/eq	#0xa,r0 	/* ascii space */
+	bf	loop
+	sub	r8,r1		/* r1 - r8 → r1 */
+	rts
+	nop
+
+	.balign 4
+start:	.long _binary_2020_day3_input_txt_start
+size:	.long _binary_2020_day3_input_txt_size
+
+	.balign 4
+stack_bot:
+	.rept 16
+	.long 0
+	.endr
+stack_top:

2020/deps.mk

@@ -0,0 +1,21 @@
+2020_DAY2_OBJ = \
+	2020/day2/solution.o \
+	2020/day2/sample.txt.o \
+	2020/day2/input.txt.o \
+	common/parse_base10.o
+
+2020/day2/solution.elf: $(2020_DAY2_OBJ)
+	$(DEFAULT_LINK)
+
+2020_DAY3_OBJ = \
+	2020/day3/solution.o \
+	2020/day3/sample.txt.o \
+	2020/day3/input.txt.o \
+	common/div32_16.o
+
+2020/day3/solution.elf: $(2020_DAY3_OBJ)
+	$(DEFAULT_LINK)
+
+ALL_ELF += \
+	2020/day2/solution.elf \
+	2020/day3/solution.elf

Makefile

@@ -28,6 +28,9 @@ CFLAGS += -ffreestanding -nostdlib
 DEPFLAGS = -MMD -MP
 LDFLAGS += --no-warn-execstack
 
+ALL_ELF =
+all:
+
 %.o: %.c
 	$(CC) $(CARCH) $(CC_ENDIAN) $(CFLAGS) $(OPT) $(DEBUG) $(DEPFLAGS) -MF ${<}.d -c $< -o $@
 
@@ -58,7 +61,7 @@ endef
 clean:
 	find -P \
 		-regextype posix-egrep \
-		-regex '.*\.(o|bin|elf|d)$$' \
+		-regex '.*\.(o|bin|elf|d|map)$$' \
 		-exec rm {} \;
 
 .SUFFIXES:
@@ -75,3 +78,6 @@ clean:
 MAKEFLAGS += --no-builtin-rules
 
 include 2019/deps.mk
+include 2020/deps.mk
+
+all: $(subst .elf,.bin,$(ALL_ELF))

common/div32_16.s

@@ -0,0 +1,18 @@
+	.global _div32_16
+	.align 4
+_div32_16:
+	/* r1 (32 bits) ÷ r0 (16 bits) */
+	shll16	r0
+	cmp/hs	r0,r1
+	bt	over_div
+	div0u
+.rept 16
+	div1	r0,r1
+.endr
+	rotcl	r1
+	rts
+	extu.w	r1,r1
+over_div:
+	bra	over_div
+	nop
+	/* r1 = quotient */

common/parse_base10.s

@@ -0,0 +1,22 @@
+	.section .text.parse_base10
+
+	.global _parse_base10
+_parse_base10:
+	/* r8 = pointer to text ; r1 = number */
+	mov	#0,r1	/* r1: accumulated number */
+parse_base10_loop:
+	mov.b 	@r8+,r2
+	add	#-48,r2 /* ascii '0' */
+	cmp/pz	r2	/* Rn >= 0 (signed)  (r2 >= 0 ) */
+	bf/s	parse_base10_rts
+	mov	#9,r4	/* const 9 */
+	cmp/ge	r2,r4	/* Rn >= Rm (signed) ( 9 >= r2) */
+	bf/s	parse_base10_rts
+	mov	#10,r4	/* const 10 */
+	mulu.w	r1,r4
+	sts	macl,r1
+	bra	parse_base10_loop
+	add	r2,r1
+parse_base10_rts:
+	rts
+	nop