[flashrom] [PATCH] Handle insufficient DOS timer precision

[Carl-Daniel Hailfinger]

Handle insufficient DOS timer precision by measuring a 100 ms delay
instead of a 100 us delay. This should reduce the likelihood of flashrom
timer complaints from 100% to 50%. If you want less complaints, use 1000
ms instead. This is mostly a proof of concept and I'd appreciate tests.

Once I know which #defines to look for on MinGW and Cygwin, I can modify
the #if to cover them as well.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

Index: flashrom-measure_delay_precision_dos/udelay.c
===================================================================
--- flashrom-measure_delay_precision_dos/udelay.c	(Revision 1008)
+++ flashrom-measure_delay_precision_dos/udelay.c	(Arbeitskopie)
@@ -93,7 +93,19 @@
 		 * a scheduler delay or something similar.
 		 */
 		for (i = 0; i < 4; i++) {
-			if (measure_delay(100) < 90) {
+#if !defined(__DJGPP__)
+			timeusec = measure_delay(100);
+#else
+			/* This zero delay workaround should be active for
+			 * DOS and Windows and maybe libpayload. The criterion
+			 * here is insufficient (worse than 100 us) OS timer
+			 * resolution which will result in measure_delay(100)=0
+			 * whereas a longer delay (100 ms) will be sufficient
+			 * to get a nonzero time measurement.
+			 */
+			timeusec = measure_delay(100000) / 1000;
+#endif
+			if (timeusec < 90) {
 				msg_pdbg("delay more than 10%% too short, "
 					 "recalculating... ");
 				goto recalibrate;


-- 
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