From: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
Date: Tue, 10 Sep 2013 19:34:44 +0000 (+0200)
Subject: further trick to optimize code size
X-Git-Tag: testing-head~23
X-Git-Url: http://git.linex4red.de/pub/USBaspLoader.git/commitdiff_plain/206b8f6f5fc48e9cc2b3432314191ffc0fc7804f

further trick to optimize code size

This is a very dangerous path to go, but it is worth it.

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@tu-ilmenau.de>
---

diff --git a/firmware/main.c b/firmware/main.c
index 8114dda..2c029b8 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -113,7 +113,13 @@ typedef union longConverter{
 
 
 #if BOOTLOADER_CAN_EXIT
-static volatile unsigned char	stayinloader = 0xfe;
+#	if ((HAVE_UNPRECISEWAIT))
+/* here we have to assume we need to optimize for every byte */
+#define __REGISTER_stayinloader_initialValue 0xfe
+volatile register uint8_t stayinloader __asm__("r17");
+#	else
+static volatile uint8_t stayinloader = 0xfe;
+#	endif
 #endif
 
 static longConverter_t  	currentAddress; /* in bytes */
@@ -196,6 +202,18 @@ static const uchar  signatureBytes[4] = {
 
 /* ------------------------------------------------------------------------ */
 
+#if (__REGISTER_stayinloader_initialValue)
+/* need to put it after libc init - otherwise it fucks up the register */
+void __attribute__ ((section(".init8"),naked,used,no_instrument_function)) __REGISTER_stayinloader_initialValue_INITIALIZATION(void);
+void __REGISTER_stayinloader_initialValue_INITIALIZATION(void) {
+  asm volatile (
+    "ldi	%[silreg]	,	%[silval]\n\t"
+    : [silreg]		"=a" (stayinloader)
+    : [silval]		"M"  (__REGISTER_stayinloader_initialValue)
+  );
+}
+#endif
+
 #if (HAVE_BOOTLOADERENTRY_FROMSOFTWARE)
 void __attribute__ ((section(".init3"),naked,used,no_instrument_function)) __BOOTLOADERENTRY_FROMSOFTWARE__bootup_investigate_RAMEND(void);
 void __BOOTLOADERENTRY_FROMSOFTWARE__bootup_investigate_RAMEND(void) {