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synthetic target implementation of HAL_DELAY_US()
- From: Bart Veer <bartv at ecoscentric dot com>
- To: ecos-patches at ecos dot sourceware dot org
- Date: Sun, 26 Jun 2005 14:00:15 +0100 (BST)
- Subject: synthetic target implementation of HAL_DELAY_US()
This adds an implementation of HAL_DELAY_US() to the synthetic target.
The bogomips rating is extracted from /proc/cpuinfo in the startup
code, and is then used by a bit of inline assembler. The results are
not quite as accurate as I would have liked. On four different
systems, with bogomips ratings of 2375, 1730, 398 and 1376
respectively, 60 seconds worth of HAL_DELAY_US() gives me 58.13,
63.98, 64.56 and 65.60 seconds. However it should be close enough -
synthetic target timing is never going to be particularly accurate
anyway.
Bart
Index: hal/synth/arch/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/synth/arch/current/ChangeLog,v
retrieving revision 1.28
diff -u -r1.28 ChangeLog
--- hal/synth/arch/current/ChangeLog 11 Mar 2005 19:04:07 -0000 1.28
+++ hal/synth/arch/current/ChangeLog 26 Jun 2005 12:49:58 -0000
@@ -1,3 +1,11 @@
+2005-06-26 Bart Veer <bartv@ecoscentric.com>
+
+ * src/synth_intr.c (synth_hardware_init): extract bogomips rating
+ for use by HAL_DELAY_US()
+
+ * include/hal_intr.h: add #include of <cyg/hal/var_intr.h> for
+ HAL_DELAY_US().
+
2005-03-11 Bart Veer <bartv@ecoscentric.com>
* src/synth_intr.c (synth_hardware_init): allow the platform to
Index: hal/synth/arch/current/include/hal_intr.h
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/synth/arch/current/include/hal_intr.h,v
retrieving revision 1.6
diff -u -r1.6 hal_intr.h
--- hal/synth/arch/current/include/hal_intr.h 9 Aug 2004 17:53:59 -0000 1.6
+++ hal/synth/arch/current/include/hal_intr.h 26 Jun 2005 12:50:02 -0000
@@ -240,6 +239,12 @@
CYG_MACRO_END
// ----------------------------------------------------------------------------
+// HAL_DELAY_US() support. The macro is provided by the processor-specific
+// HAL, but the bogomips rating is provided by the architectural code.
+extern int hal_bogomips;
+#include <cyg/hal/var_intr.h>
+
+// ----------------------------------------------------------------------------
// Resetting the Synth target is not possible, but existing the process is.
externC void cyg_hal_sys_exit(int);
#define HAL_PLATFORM_RESET() \
Index: hal/synth/arch/current/src/synth_intr.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/synth/arch/current/src/synth_intr.c,v
retrieving revision 1.7
diff -u -r1.7 synth_intr.c
--- hal/synth/arch/current/src/synth_intr.c 11 Mar 2005 19:04:06 -0000 1.7
+++ hal/synth/arch/current/src/synth_intr.c 26 Jun 2005 12:50:07 -0000
@@ -129,6 +129,9 @@
// ----------------------------------------------------------------------------
// Statics.
+// The bogomips rating, used by HAL_DELAY_US()
+int hal_bogomips;
+
// Are interrupts currently enabled?
volatile cyg_bool_t hal_interrupts_enabled = false;
@@ -1325,6 +1328,42 @@
CYG_FAIL("Failed to install signal handler for SIGCHLD");
}
+ // Determine the processor's bogomips rating. This adds some
+ // start-up overhead to all applications, even if HAL_DELAY_US()
+ // is not used. However doing it on demand in the first call
+ // to HAL_DELAY_US() would risk running out of file descriptors.
+ {
+ int fd;
+ char buf[4096]; // much larger than current /proc/cpuinfo, but still small enough for synthetic target stacks
+ int read;
+ int i;
+
+ fd = cyg_hal_sys_open("/proc/cpuinfo", CYG_HAL_SYS_O_RDONLY, 0);
+ if (fd < 0) {
+ CYG_FAIL("Failed to open /proc/cpuinfo, needed for BogoMips rating");
+ }
+ read = cyg_hal_sys_read(fd, buf, 4096);
+ cyg_hal_sys_close(fd);
+
+ for (i = 0; i < read; i++) {
+ if ((buf[i ] == 'b') && (buf[i+1] == 'o') && (buf[i+2] == 'g') && (buf[i+3] == 'o') &&
+ (buf[i+4] == 'm') && (buf[i+5] == 'i') && (buf[i+6] == 'p') && (buf[i+7] == 's')) {
+
+ for ( i += 8; (i < read) && ((buf[i] < '1') || (buf[i] > '9')); i++) {
+ ;
+ }
+ // Only bother with the integer part of the rating
+ for ( ; (i < read) && (buf[i] >= '0') && (buf[i] <= '9'); i++) {
+ hal_bogomips = (10 * hal_bogomips) + (buf[i] - '0');
+ }
+ break;
+ }
+ }
+ if (0 == hal_bogomips) {
+ CYG_FAIL("Failed to find bogomips entry in /proc/cpuinfo");
+ }
+ }
+
// Start up the auxiliary process.
synth_start_auxiliary();
Index: hal/synth/i386linux/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/synth/i386linux/current/ChangeLog,v
retrieving revision 1.14
diff -u -r1.14 ChangeLog
--- hal/synth/i386linux/current/ChangeLog 21 Mar 2005 14:37:03 -0000 1.14
+++ hal/synth/i386linux/current/ChangeLog 26 Jun 2005 12:50:44 -0000
@@ -1,3 +1,8 @@
+2005-06-26 Bart Veer <bartv@ecoscentric.com>
+
+ * include/var_intr.h (HAL_DELAY_US): new header to supply
+ processor-specific HAL_DELAY_US() macro
+
2005-03-21 Bart Veer <bartv@ecoscentric.com>
* cdl/hal_synth_i386.cdl, src/profile.c: add profiling support.
Index: hal/synth/i386linux/current/include/var_intr.h
===================================================================
RCS file: hal/synth/i386linux/current/include/var_intr.h
diff -N hal/synth/i386linux/current/include/var_intr.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ hal/synth/i386linux/current/include/var_intr.h 26 Jun 2005 12:50:45 -0000
@@ -0,0 +1,76 @@
+#ifndef CYGONCE_HAL_VAR_INTR_H
+#define CYGONCE_HAL_VAR_INTR_H
+
+//=============================================================================
+//
+// var_intr.h
+//
+// Processor-specific interrupt support
+//
+//=============================================================================
+//####ECOSGPLCOPYRIGHTBEGIN####
+// -------------------------------------------
+// This file is part of eCos, the Embedded Configurable Operating System.
+// Copyright (C) 2005 eCosCentric Ltd.
+//
+// eCos is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 2 or (at your option) any later version.
+//
+// eCos 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 General Public License
+// for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with eCos; if not, write to the Free Software Foundation, Inc.,
+// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+//
+// As a special exception, if other files instantiate templates or use macros
+// or inline functions from this file, or you compile this file and link it
+// with other works to produce a work based on this file, this file does not
+// by itself cause the resulting work to be covered by the GNU General Public
+// License. However the source code for this file must still be made available
+// in accordance with section (3) of the GNU General Public License.
+//
+// This exception does not invalidate any other reasons why a work based on
+// this file might be covered by the GNU General Public License.
+// -------------------------------------------
+//####ECOSGPLCOPYRIGHTEND####
+//=============================================================================
+//#####DESCRIPTIONBEGIN####
+//
+// Author(s): bartv
+// Date: 2005-06-26
+// Usage: #include <cyg/hal/hal_intr.h>
+//
+//####DESCRIPTIONEND####
+//
+//=============================================================================
+
+// The architectural HAL provides the bogomips rating. This is an
+// outer loop for the number of us and an inner loop for 1us. The
+// alignment of the inner loop can greatly affect performance. The
+// *16 of the bogomips rating seems to give about the right results
+// on a range of hardware.
+#define HAL_DELAY_US(_us_) \
+ CYG_MACRO_START \
+ asm volatile ( \
+ "1:\n" \
+ "movl %2,%1\n" \
+ "sal $0x4,%1\n" \
+ ".align 16\n" \
+ "2:\n" \
+ "decl %1\n" \
+ "jns 2b\n" \
+ "decl %0\n" \
+ "jns 1b\n" \
+ : \
+ : "r" (_us_), "r" (0), "g" (hal_bogomips+1) \
+ : "cc"); \
+ CYG_MACRO_END
+
+
+//--------------------------------------------------------------------------
+#endif // CYGONCE_HAL_VAR_INTR_H
+// End of var_intr.h