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Adding disassembly and polishing the Notes.md

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Per 2019-09-29 15:53:26 +02:00
parent 31af041cce
commit b01aef6461
3 changed files with 206 additions and 2 deletions
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5
Cargo.toml
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@ -45,8 +45,11 @@ required-features = ["__v7"]
name = "types"
required-features = ["__v7"]
[dependencies.cortex-m]
version = "0.6.0"
features = ["inline-asm"]
[dependencies]
cortex-m = "0.6.0"
cortex-m-rtfm-macros = { path = "macros" }
rtfm-core = "0.3.0-beta.1"
cortex-m-rt = "0.6.9"

30
Notes.md
View file

@ -147,6 +147,34 @@ Overall, using this approach, we don't need a trampoline (`run`). We reduce the
The `examples/lockopt.rs` shows that locks are effectively optimized out.
Old Implementation
``` asm
00000130 <GPIOB>:
130: 21a0 movs r1, #160 ; 0xa0
132: f3ef 8011 mrs r0, BASEPRI
136: f381 8811 msr BASEPRI, r1
13a: f240 0100 movw r1, #0
13e: f2c2 0100 movt r1, #8192 ; 0x2000
142: 680a ldr r2, [r1, #0]
144: 3201 adds r2, #1
146: 600a str r2, [r1, #0]
148: 21c0 movs r1, #192 ; 0xc0
14a: f381 8811 msr BASEPRI, r1
14e: f380 8811 msr BASEPRI, r0
152: 4770 bx lr
00000154 <GPIOC>:
154: f240 0100 movw r1, #0
158: f3ef 8011 mrs r0, BASEPRI
15c: f2c2 0100 movt r1, #8192 ; 0x2000
160: 680a ldr r2, [r1, #0]
162: 3202 adds r2, #2
164: 600a str r2, [r1, #0]
166: f380 8811 msr BASEPRI, r0
16a: 4770 bx lr
```
With lock opt. We see a 20% improvement for short/small tasks.
``` asm
00000128 <GPIOB>:
128: 21a0 movs r1, #160 ; 0xa0
@ -169,7 +197,7 @@ The `examples/lockopt.rs` shows that locks are effectively optimized out.
154: 4770 bx lr
```
GPIOB/C are sharing a resource (C higher prio). Notice, there is no BASEPRI manipulation at all.
GPIOB/C are sharing a resource (C higher prio). Notice, for GPIOC there is no BASEPRI manipulation at all.
For GPIOB, there is a single read of BASEPRI (stored in `old_basepri_hw`) and just two writes, one for entering critical section, one for exiting. On exit we detect that we are indeed at the initial priority for the task, thus we restore the `old_basepri_hw` instead of a logic priority.

173
lockopt_vanilla.asm Normal file
View file

@ -0,0 +1,173 @@
target/thumbv7m-none-eabi/release/examples/lockopt: file format elf32-littlearm
Disassembly of section .text:
000000f0 <GPIOA>:
f0: b580 push {r7, lr}
f2: 20a0 movs r0, #160 ; 0xa0
f4: f380 8811 msr BASEPRI, r0
f8: f240 0000 movw r0, #0
fc: f2c2 0000 movt r0, #8192 ; 0x2000
100: 6801 ldr r1, [r0, #0]
102: 3101 adds r1, #1
104: 6001 str r1, [r0, #0]
106: f24e 2000 movw r0, #57856 ; 0xe200
10a: 2102 movs r1, #2
10c: f2ce 0000 movt r0, #57344 ; 0xe000
110: 6001 str r1, [r0, #0]
112: 2104 movs r1, #4
114: 6001 str r1, [r0, #0]
116: 2126 movs r1, #38 ; 0x26
118: 20e0 movs r0, #224 ; 0xe0
11a: f380 8811 msr BASEPRI, r0
11e: f2c0 0102 movt r1, #2
122: 2018 movs r0, #24
124: f000 f892 bl 24c <__syscall>
128: 2000 movs r0, #0
12a: f380 8811 msr BASEPRI, r0
12e: bd80 pop {r7, pc}
00000130 <GPIOB>:
130: 21a0 movs r1, #160 ; 0xa0
132: f3ef 8011 mrs r0, BASEPRI
136: f381 8811 msr BASEPRI, r1
13a: f240 0100 movw r1, #0
13e: f2c2 0100 movt r1, #8192 ; 0x2000
142: 680a ldr r2, [r1, #0]
144: 3201 adds r2, #1
146: 600a str r2, [r1, #0]
148: 21c0 movs r1, #192 ; 0xc0
14a: f381 8811 msr BASEPRI, r1
14e: f380 8811 msr BASEPRI, r0
152: 4770 bx lr
00000154 <GPIOC>:
154: f240 0100 movw r1, #0
158: f3ef 8011 mrs r0, BASEPRI
15c: f2c2 0100 movt r1, #8192 ; 0x2000
160: 680a ldr r2, [r1, #0]
162: 3202 adds r2, #2
164: 600a str r2, [r1, #0]
166: f380 8811 msr BASEPRI, r0
16a: 4770 bx lr
0000016c <main>:
16c: f24e 1000 movw r0, #57600 ; 0xe100
170: f24e 4201 movw r2, #58369 ; 0xe401
174: f2ce 0000 movt r0, #57344 ; 0xe000
178: 21e0 movs r1, #224 ; 0xe0
17a: b672 cpsid i
17c: f880 1300 strb.w r1, [r0, #768] ; 0x300
180: 2101 movs r1, #1
182: f2ce 0200 movt r2, #57344 ; 0xe000
186: 23c0 movs r3, #192 ; 0xc0
188: 6001 str r1, [r0, #0]
18a: 7013 strb r3, [r2, #0]
18c: 2302 movs r3, #2
18e: 6003 str r3, [r0, #0]
190: 23a0 movs r3, #160 ; 0xa0
192: 7053 strb r3, [r2, #1]
194: 2204 movs r2, #4
196: 6002 str r2, [r0, #0]
198: f64e 5210 movw r2, #60688 ; 0xed10
19c: f2ce 0200 movt r2, #57344 ; 0xe000
1a0: 6813 ldr r3, [r2, #0]
1a2: f043 0302 orr.w r3, r3, #2
1a6: 6013 str r3, [r2, #0]
1a8: f8c0 1100 str.w r1, [r0, #256] ; 0x100
1ac: b662 cpsie i
1ae: bf30 wfi
1b0: e7fd b.n 1ae <main+0x42>
000001b2 <Reset>:
1b2: f000 f84a bl 24a <DefaultPreInit>
1b6: f240 0004 movw r0, #4
1ba: f240 0100 movw r1, #0
1be: f2c2 0000 movt r0, #8192 ; 0x2000
1c2: f2c2 0100 movt r1, #8192 ; 0x2000
1c6: 4281 cmp r1, r0
1c8: d214 bcs.n 1f4 <Reset+0x42>
1ca: f240 0100 movw r1, #0
1ce: 2200 movs r2, #0
1d0: f2c2 0100 movt r1, #8192 ; 0x2000
1d4: f841 2b04 str.w r2, [r1], #4
1d8: 4281 cmp r1, r0
1da: bf3c itt cc
1dc: f841 2b04 strcc.w r2, [r1], #4
1e0: 4281 cmpcc r1, r0
1e2: d207 bcs.n 1f4 <Reset+0x42>
1e4: f841 2b04 str.w r2, [r1], #4
1e8: 4281 cmp r1, r0
1ea: d203 bcs.n 1f4 <Reset+0x42>
1ec: f841 2b04 str.w r2, [r1], #4
1f0: 4281 cmp r1, r0
1f2: d3ef bcc.n 1d4 <Reset+0x22>
1f4: f240 0000 movw r0, #0
1f8: f240 0100 movw r1, #0
1fc: f2c2 0000 movt r0, #8192 ; 0x2000
200: f2c2 0100 movt r1, #8192 ; 0x2000
204: 4281 cmp r1, r0
206: d21c bcs.n 242 <Reset+0x90>
208: f240 2168 movw r1, #616 ; 0x268
20c: f240 0200 movw r2, #0
210: f2c0 0100 movt r1, #0
214: f2c2 0200 movt r2, #8192 ; 0x2000
218: 680b ldr r3, [r1, #0]
21a: f842 3b04 str.w r3, [r2], #4
21e: 4282 cmp r2, r0
220: d20f bcs.n 242 <Reset+0x90>
222: 684b ldr r3, [r1, #4]
224: f842 3b04 str.w r3, [r2], #4
228: 4282 cmp r2, r0
22a: bf3e ittt cc
22c: 688b ldrcc r3, [r1, #8]
22e: f842 3b04 strcc.w r3, [r2], #4
232: 4282 cmpcc r2, r0
234: d205 bcs.n 242 <Reset+0x90>
236: 68cb ldr r3, [r1, #12]
238: 3110 adds r1, #16
23a: f842 3b04 str.w r3, [r2], #4
23e: 4282 cmp r2, r0
240: d3ea bcc.n 218 <Reset+0x66>
242: f7ff ff93 bl 16c <main>
246: defe udf #254 ; 0xfe
00000248 <DefaultHandler_>:
248: Address 0x0000000000000248 is out of bounds.
00000249 <ADC0_SEQUENCE_0>:
249: Address 0x0000000000000249 is out of bounds.
0000024a <DefaultPreInit>:
24a: Address 0x000000000000024a is out of bounds.
0000024b <__pre_init>:
24b: Address 0x000000000000024b is out of bounds.
0000024c <__syscall>:
24c: beab bkpt 0x00ab
24e: 4770 bx lr
00000250 <HardFaultTrampoline>:
250: 4670 mov r0, lr
252: 2104 movs r1, #4
254: 4208 tst r0, r1
256: d102 bne.n 25e <HardFaultTrampoline+0xe>
258: f3ef 8008 mrs r0, MSP
25c: e002 b.n 264 <HardFault_>
25e: f3ef 8009 mrs r0, PSP
262: e7ff b.n 264 <HardFault_>
00000264 <HardFault_>:
264: Address 0x0000000000000264 is out of bounds.
00000265 <HardFault>:
265: Address 0x0000000000000265 is out of bounds.