Added pulseIn implementation

cores/arduino/Arduino.h

@@ -71,7 +71,7 @@ void loop( void ) ;
   #include "Tone.h"
   #include "WMath.h"
   #include "HardwareSerial.h"
-//  #include "wiring_pulse.h"
+  #include "pulse.h"
   #include "delay.h"
   #include "Uart.h"
 #endif // __cplusplus

cores/arduino/pulse.c

@@ -0,0 +1,52 @@
+/*
+  Copyright (c) 2015 Arduino LLC.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#include <Arduino.h>
+
+// See pulse_asm.S
+extern unsigned long countPulseASM(const volatile uint32_t *port, uint32_t bit, uint32_t stateMask, unsigned long maxloops);
+
+/* Measures the length (in microseconds) of a pulse on the pin; state is HIGH
+ * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
+ * to 3 minutes in length, but must be called at least a few dozen microseconds
+ * before the start of the pulse. */
+uint32_t pulseIn(uint32_t pin, uint32_t state, uint32_t timeout)
+{
+  // cache the port and bit of the pin in order to speed up the
+  // pulse width measuring loop and achieve finer resolution.  calling
+  // digitalRead() instead yields much coarser resolution.
+  PinDescription p = g_APinDescription[pin];
+  uint32_t bit = 1 << p.ulPin;
+  uint32_t stateMask = state ? bit : 0;
+
+  // convert the timeout from microseconds to a number of times through
+  // the initial loop; it takes (roughly) 13 clock cycles per iteration.
+  uint32_t maxloops = microsecondsToClockCycles(timeout) / 13;
+
+  uint32_t width = countPulseASM(&(PORT->Group[p.ulPort].IN.reg), bit, stateMask, maxloops);
+
+  // convert the reading to microseconds. The loop has been determined
+  // to be 13 clock cycles long and have about 16 clocks between the edge
+  // and the start of the loop. There will be some error introduced by
+  // the interrupt handlers.
+  if (width)
+    return clockCyclesToMicroseconds(width * 13 + 16);
+  else
+    return 0;
+}
+

cores/arduino/pulse.h

@@ -0,0 +1,39 @@
+/*
+  Copyright (c) 2015 Arduino LLC.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * \brief Measures the length (in microseconds) of a pulse on the pin; state is HIGH
+ * or LOW, the type of pulse to measure.  Works on pulses from 2-3 microseconds
+ * to 3 minutes in length, but must be called at least a few dozen microseconds
+ * before the start of the pulse.
+ */
+uint32_t pulseIn(uint32_t pin, uint32_t state, uint32_t timeout);
+
+#ifdef __cplusplus
+// Provides a version of pulseIn with a default argument (C++ only)
+uint32_t pulseIn(uint32_t pin, uint32_t state, uint32_t timeout = 1000000L);
+
+} // extern "C"
+#endif
+

cores/arduino/pulse_asm.S

@@ -0,0 +1,175 @@
+/*
+  Copyright (c) 2015 Arduino LLC.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the GNU Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+/*
+
+The following function has been compiled to ASM with gcc
+
+    unsigned long countPulseASM(const volatile uint32_t *port, uint32_t bit, uint32_t stateMask, unsigned long maxloops)
+    {
+      unsigned long width = 0;
+
+      // wait for any previous pulse to end
+      while ((*port & bit) == stateMask)
+        if (--maxloops == 0)
+          return 0;
+
+      // wait for the pulse to start
+      while ((*port & bit) != stateMask)
+        if (--maxloops == 0)
+          return 0;
+
+      // wait for the pulse to stop
+      while ((*port & bit) == stateMask) {
+        if (++width == maxloops)
+          return 0;
+      }
+      return width;
+    }
+
+using the command line:
+
+    arm-none-eabi-gcc -mcpu=cortex-m0plus -mthumb -c -Os -W -ffunction-sections -fdata-sections \
+                      -nostdlib --param max-inline-insns-single=500 -fno-exceptions -MMD \
+                      -DF_CPU=48000000L -DARDUINO=10602 -DARDUINO_SAMD_ZERO -DARDUINO_ARCH_SAMD \
+                      -D__SAMD21G18A__ -DUSB_VID=0x2341 -DUSB_PID=0x004d -DUSBCON \
+                      -DUSB_MANUFACTURER="Arduino LLC" -DUSB_PRODUCT="Arduino Zero" \
+                      -I/Code/arduino/build/linux/work/hardware/tools/CMSIS/CMSIS/Include/ \
+                      -I/Code/arduino/build/linux/work/hardware/tools/CMSIS/Device/ATMEL/ \
+                      -I/Code/arduino/build/linux/work/hardware/arduino/samd/cores/arduino \
+                      -I/Code/arduino/build/linux/work/hardware/arduino/samd/variants/arduino_zero \
+                      count.c -Wa,-ahlmsd=output.lst -dp -fverbose-asm -S
+
+The result has been slightly edited to increase readability.
+
+*/
+
+	.cpu cortex-m0plus
+	.fpu softvfp
+	.eabi_attribute 20, 1	@ Tag_ABI_FP_denormal
+	.eabi_attribute 21, 1	@ Tag_ABI_FP_exceptions
+	.eabi_attribute 23, 3	@ Tag_ABI_FP_number_model
+	.eabi_attribute 24, 1	@ Tag_ABI_align8_needed
+	.eabi_attribute 25, 1	@ Tag_ABI_align8_preserved
+	.eabi_attribute 26, 1	@ Tag_ABI_enum_size
+	.eabi_attribute 30, 4	@ Tag_ABI_optimization_goals
+	.eabi_attribute 34, 0	@ Tag_CPU_unaligned_access
+	.eabi_attribute 18, 4	@ Tag_ABI_PCS_wchar_t
+	.file	"count.c"
+@ GNU C (GNU Tools for ARM Embedded Processors (Arduino build)) version 4.8.3 20140228 (release) [ARM/embedded-4_8-branch revision 208322] (arm-none-eabi)
+@	compiled by GNU C version 4.3.2, GMP version 4.3.2, MPFR version 2.4.2, MPC version 0.8.1
+@ GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
+@ options passed: 
+@ -I /Code/arduino/build/linux/work/hardware/tools/CMSIS/CMSIS/Include/
+@ -I /Code/arduino/build/linux/work/hardware/tools/CMSIS/Device/ATMEL/
+@ -I /Code/arduino/build/linux/work/hardware/arduino/samd/cores/arduino
+@ -I /Code/arduino/build/linux/work/hardware/arduino/samd/variants/arduino_zero
+@ -imultilib armv6-m
+@ -iprefix /Code/arduino/build/linux/work/hardware/tools/gcc-arm-none-eabi-4.8.3-2014q1/bin/../lib/gcc/arm-none-eabi/4.8.3/
+@ -isysroot /Code/arduino/build/linux/work/hardware/tools/gcc-arm-none-eabi-4.8.3-2014q1/bin/../arm-none-eabi
+@ -MMD count.d -D__USES_INITFINI__ -D F_CPU=48000000L -D ARDUINO=10602
+@ -D ARDUINO_SAMD_ZERO -D ARDUINO_ARCH_SAMD -D __SAMD21G18A__
+@ -D USB_VID=0x2341 -D USB_PID=0x004d -D USBCON
+@ -D USB_MANUFACTURER=Arduino LLC -D USB_PRODUCT=Arduino Zero count.c
+@ -mcpu=cortex-m0plus -mthumb -Os -Wextra -ffunction-sections
+@ -fdata-sections -fno-exceptions -fverbose-asm
+@ --param max-inline-insns-single=500
+@ options enabled:  -faggressive-loop-optimizations -fauto-inc-dec
+@ -fbranch-count-reg -fcaller-saves -fcombine-stack-adjustments -fcommon
+@ -fcompare-elim -fcprop-registers -fcrossjumping -fcse-follow-jumps
+@ -fdata-sections -fdefer-pop -fdelete-null-pointer-checks -fdevirtualize
+@ -fdwarf2-cfi-asm -fearly-inlining -feliminate-unused-debug-types
+@ -fexpensive-optimizations -fforward-propagate -ffunction-cse
+@ -ffunction-sections -fgcse -fgcse-lm -fgnu-runtime
+@ -fguess-branch-probability -fhoist-adjacent-loads -fident -fif-conversion
+@ -fif-conversion2 -findirect-inlining -finline -finline-atomics
+@ -finline-functions -finline-functions-called-once
+@ -finline-small-functions -fipa-cp -fipa-profile -fipa-pure-const
+@ -fipa-reference -fipa-sra -fira-hoist-pressure -fira-share-save-slots
+@ -fira-share-spill-slots -fivopts -fkeep-static-consts
+@ -fleading-underscore -fmath-errno -fmerge-constants -fmerge-debug-strings
+@ -fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls
+@ -fpartial-inlining -fpeephole -fpeephole2 -fprefetch-loop-arrays
+@ -freg-struct-return -fregmove -freorder-blocks -freorder-functions
+@ -frerun-cse-after-loop -fsched-critical-path-heuristic
+@ -fsched-dep-count-heuristic -fsched-group-heuristic -fsched-interblock
+@ -fsched-last-insn-heuristic -fsched-pressure -fsched-rank-heuristic
+@ -fsched-spec -fsched-spec-insn-heuristic -fsched-stalled-insns-dep
+@ -fschedule-insns2 -fsection-anchors -fshow-column -fshrink-wrap
+@ -fsigned-zeros -fsplit-ivs-in-unroller -fsplit-wide-types
+@ -fstrict-aliasing -fstrict-overflow -fstrict-volatile-bitfields
+@ -fsync-libcalls -fthread-jumps -ftoplevel-reorder -ftrapping-math
+@ -ftree-bit-ccp -ftree-builtin-call-dce -ftree-ccp -ftree-ch
+@ -ftree-coalesce-vars -ftree-copy-prop -ftree-copyrename -ftree-cselim
+@ -ftree-dce -ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre
+@ -ftree-loop-if-convert -ftree-loop-im -ftree-loop-ivcanon
+@ -ftree-loop-optimize -ftree-parallelize-loops= -ftree-phiprop -ftree-pre
+@ -ftree-pta -ftree-reassoc -ftree-scev-cprop -ftree-sink
+@ -ftree-slp-vectorize -ftree-slsr -ftree-sra -ftree-switch-conversion
+@ -ftree-tail-merge -ftree-ter -ftree-vect-loop-version -ftree-vrp
+@ -funit-at-a-time -fverbose-asm -fzero-initialized-in-bss -mlittle-endian
+@ -mpic-data-is-text-relative -msched-prolog -mthumb
+@ -mvectorize-with-neon-quad
+
+	.section	.text.countPulseASM,"ax",%progbits
+	.align	1
+	.global	countPulseASM
+	.code	16
+	.thumb_func
+	.type	countPulseASM, %function
+countPulseASM:
+	push	{r4, r5, lr}	@			@ 112	*push_multi		[length = 2]
+.L2:
+	ldr	r4, [r0]	@ D.11539, *port_7(D)	@ 22	*thumb1_movsi_insn/7	[length = 2]
+	and	r4, r1		@ D.11539, bit		@ 24	*thumb1_andsi3_insn	[length = 2]
+	cmp	r4, r2		@ D.11539, stateMask	@ 25	cbranchsi4_insn/1	[length = 4]
+	bne	.L5		@,
+	sub	r3, r3, #1	@ maxloops,		@ 17	*thumb1_addsi3/2	[length = 2]
+	cmp	r3, #0		@ maxloops,		@ 18	cbranchsi4_insn/1	[length = 4]
+	bne	.L2		@,
+	b	.L10		@			@ 127	*thumb_jump		[length = 2]
+.L6:
+	sub	r3, r3, #1	@ maxloops,		@ 30	*thumb1_addsi3/2	[length = 2]
+	cmp	r3, #0		@ maxloops,		@ 31	cbranchsi4_insn/1	[length = 4]
+	beq	.L10		@,
+.L5:
+	ldr	r4, [r0]	@ D.11539, *port_7(D)	@ 35	*thumb1_movsi_insn/7	[length = 2]
+	and	r4, r1		@ D.11539, bit		@ 37	*thumb1_andsi3_insn	[length = 2]
+	cmp	r4, r2		@ D.11539, stateMask	@ 38	cbranchsi4_insn/1	[length = 4]
+	bne	.L6		@,
+	mov	r4, #0		@ width,		@ 7	*thumb1_movsi_insn/2	[length = 2]
+.L7:
+	ldr	r5, [r0]	@ D.11539, *port_7(D)	@ 48	*thumb1_movsi_insn/7	[length = 2]
+	and	r5, r1		@ D.11539, bit		@ 50	*thumb1_andsi3_insn	[length = 2]
+	cmp	r5, r2		@ D.11539, stateMask	@ 51	cbranchsi4_insn/1	[length = 4]
+	bne	.L13		@,
+	add	r4, r4, #1	@ width,		@ 43	*thumb1_addsi3/1	[length = 2]
+	cmp	r4, r3		@ width, maxloops	@ 44	cbranchsi4_insn/1	[length = 4]
+	bne	.L7		@,
+	mov	r0, #0		@ D.11539,		@ 11	*thumb1_movsi_insn/2	[length = 2]
+	b	.L3		@			@ 130	*thumb_jump		[length = 2]
+.L13:
+	mov	r0, r4		@ D.11539, width	@ 9	*thumb1_movsi_insn/1	[length = 2]
+	b	.L3		@			@ 132	*thumb_jump		[length = 2]
+.L10:
+	mov	r0, r3		@ D.11539, maxloops	@ 8	*thumb1_movsi_insn/1	[length = 2]
+.L3:
+	@ sp needed		@			@ 115	force_register_use	[length = 0]
+	pop	{r4, r5, pc}
+	.size	countPulseASM, .-countPulseASM
+	.ident	"GCC: (GNU Tools for ARM Embedded Processors (Arduino build)) 4.8.3 20140228 (release) [ARM/embedded-4_8-branch revision 208322]"