optimisation: compare uint16_t against uint16_t in FinishHomingAndPlanMoveToParkPos

[gudnimg]

AxisDistance returns uint16_t type and is currently compared with long double axis length. The axis lengths fit easily into uint16_t:

selectorLimits.lenght = 75.0
idlerLimits.lenght = 225.0

Change in memory:
Flash: -122 bytes
SRAM: 0 bytes

---

Below is the changes to the assembly output for the selector limits. This optimisation removes a call to __floatunsisf and __cmpsf2

Before

if (AxisDistance(mm::axisUnitToTruncatedUnit<config::U_mm>(mm::motion.CurPosition<mm::Selector>())) < (config::selectorLimits.lenght.v - 3)) { //@@TODO is 3mm ok?
    2174:	ce 01       	movw	r24, r28
    2176:	0e 94 79 07 	call	0xef2	; 0xef2 <modules::motion::MovableBase::AxisDistance(long) const>
    217a:	bc 01       	movw	r22, r24
    217c:	90 e0       	ldi	r25, 0x00	; 0
    217e:	80 e0       	ldi	r24, 0x00	; 0
    2180:	0e 94 93 34 	call	0x6926	; 0x6926 <__floatunsisf>
    2184:	20 e0       	ldi	r18, 0x00	; 0
    2186:	30 e0       	ldi	r19, 0x00	; 0
    2188:	40 e9       	ldi	r20, 0x90	; 144
    218a:	52 e4       	ldi	r21, 0x42	; 66
    218c:	0e 94 58 34 	call	0x68b0	; 0x68b0 <__cmpsf2>
    2190:	87 fd       	sbrc	r24, 7
    2192:	1a c0       	rjmp	.+52     	; 0x21c8 <modules::selector::Selector::FinishHomingAndPlanMoveToParkPos()+0x70>
    2194:	88 e9       	ldi	r24, 0x98	; 152
    2196:	9a e3       	ldi	r25, 0x3A	; 58
    2198:	a0 e0       	ldi	r26, 0x00	; 0
    219a:	b0 e0       	ldi	r27, 0x00	; 0
    219c:	80 93 8b 05 	sts	0x058B, r24	; 0x80058b <modules::motion::motion+0x142>
    21a0:	90 93 8c 05 	sts	0x058C, r25	; 0x80058c <modules::motion::motion+0x143>
    21a4:	a0 93 8d 05 	sts	0x058D, r26	; 0x80058d <modules::motion::motion+0x144>
    21a8:	b0 93 8e 05 	sts	0x058E, r27	; 0x80058e <modules::motion::motion+0x145>

After:

if (AxisDistance(mm::axisUnitToTruncatedUnit<config::U_mm>(mm::motion.CurPosition<mm::Selector>())) < uint16_t(config::selectorLimits.lenght.v - 3)) { //@@TODO is 3mm ok?
    2174:	ce 01       	movw	r24, r28
    2176:	0e 94 79 07 	call	0xef2	; 0xef2 <modules::motion::MovableBase::AxisDistance(long) const>
    217a:	88 34       	cpi	r24, 0x48	; 72
    217c:	91 05       	cpc	r25, r1
    217e:	d0 f0       	brcs	.+52     	; 0x21b4 <modules::selector::Selector::FinishHomingAndPlanMoveToParkPos()+0x5c>
    2180:	88 e9       	ldi	r24, 0x98	; 152
    2182:	9a e3       	ldi	r25, 0x3A	; 58
    2184:	a0 e0       	ldi	r26, 0x00	; 0
    2186:	b0 e0       	ldi	r27, 0x00	; 0
    2188:	80 93 8b 05 	sts	0x058B, r24	; 0x80058b <modules::motion::motion+0x142>
    218c:	90 93 8c 05 	sts	0x058C, r25	; 0x80058c <modules::motion::motion+0x143>
    2190:	a0 93 8d 05 	sts	0x058D, r26	; 0x80058d <modules::motion::motion+0x144>
    2194:	b0 93 8e 05 	sts	0x058E, r27	; 0x80058e <modules::motion::motion+0x145>

[github-actions]

All values in bytes. Δ Delta to base

ΔFlash	ΔSRAM	Used Flash	Used SRAM	Free Flash	Free SRAM
-122	0	28132	1667	540	893

[gudnimg]

To add to the PR description... you will notice that applying this optimisation on only one of the if statements does not save a lot of resources. However, once you apply it to both if statements, __cmpsf2 is entirely removed from the firmware image. I suspect majority of the savings come from that.

For reference (https://gcc.gnu.org/onlinedocs/gccint/Soft-float-library-routines.html), what does __cmpsf2 do? It essentially compares two floating point values. We try to eliminate all floating point operations in the MMU firmware.

[DRracer]

nice catch 👍 , please carry on 🙏 ... the compiler is not very intelligent

[github-actions]

Automated Test Code Coverage Report

View details...

File	Lines	Exec	Cover
src/application.cpp	169	14	8%
src/application.h	3	3	100%
src/hal/circular_buffer.h	52	52	100%
src/hal/eeprom.h	1	0	0%
src/hal/gpio.h	18	7	38%
src/hal/progmem.h	6	6	100%
src/hal/tmc2130.cpp	113	9	7%
src/hal/tmc2130.h	31	27	87%
src/logic/command_base.cpp	139	118	84%
src/logic/command_base.h	4	3	75%
src/logic/cut_filament.cpp	117	80	68%
src/logic/eject_filament.cpp	77	60	77%
src/logic/feed_to_bondtech.cpp	60	57	95%
src/logic/feed_to_bondtech.h	1	1	100%
src/logic/feed_to_finda.cpp	48	45	93%
src/logic/feed_to_finda.h	1	1	100%
src/logic/home.cpp	18	12	66%
src/logic/load_filament.cpp	85	77	90%
src/logic/load_filament.h	1	0	0%
src/logic/move_selector.cpp	21	0	0%
src/logic/no_command.h	2	1	50%
src/logic/retract_from_finda.cpp	27	21	77%
src/logic/retract_from_finda.h	1	1	100%
src/logic/set_mode.cpp	5	0	0%
src/logic/set_mode.h	1	0	0%
src/logic/start_up.cpp	38	26	68%
src/logic/start_up.h	4	4	100%
src/logic/tool_change.cpp	108	82	75%
src/logic/unload_filament.cpp	76	69	90%
src/logic/unload_to_finda.cpp	40	39	97%
src/logic/unload_to_finda.h	1	1	100%
src/modules/axisunit.h	21	21	100%
src/modules/buttons.cpp	11	11	100%
src/modules/buttons.h	7	7	100%
src/modules/crc.h	13	13	100%
src/modules/debouncer.cpp	28	24	85%
src/modules/debouncer.h	7	7	100%
src/modules/finda.cpp	7	3	42%
src/modules/finda.h	2	2	100%
src/modules/fsensor.cpp	6	6	100%
src/modules/fsensor.h	3	3	100%
src/modules/globals.cpp	47	42	89%
src/modules/globals.h	34	24	70%
src/modules/idler.cpp	89	82	92%
src/modules/idler.h	12	12	100%
src/modules/leds.cpp	44	42	95%
src/modules/leds.h	16	15	93%
src/modules/math.h	6	6	100%
src/modules/motion.cpp	59	40	67%
src/modules/motion.h	66	64	96%
src/modules/movable_base.cpp	73	70	95%
src/modules/movable_base.h	16	16	100%
src/modules/permanent_storage.cpp	144	89	61%
src/modules/protocol.cpp	216	184	85%
src/modules/protocol.h	72	70	97%
src/modules/pulley.cpp	33	25	75%
src/modules/pulley.h	8	5	62%
src/modules/pulse_gen.cpp	95	89	93%
src/modules/pulse_gen.h	53	51	96%
src/modules/selector.cpp	69	62	89%
src/modules/selector.h	5	5	100%
src/modules/speed_table.h	26	24	92%
src/modules/user_input.cpp	39	39	100%
src/modules/user_input.h	12	12	100%
src/modules/voltage.cpp	4	0	0%
src/registers.cpp	104	37	35%
src/unit.h	12	12	100%
TOTAL	2727	2030	74%

TOTAL: 2727 lines of code, 2030 lines executed, 74% covered.

[gudnimg]

Rebased to sync with main. Will merge if all CI checks pass again.