#ENABLE_UNSAFE_OPTIMIZATIONS

Added new global flag to enable unsafe optimizations:

This will disable several safety features in microncleus to save around
40 more bytes

Disabled features:
* Stack pointer and SREG initialization in CRT
* Client side reset vector patching
* USB collision detection. Micronucleus will not work reliability with
hubs if this is disabled.

See t85_aggressive configuration for usage examples.

6 files changed, 28 insertions, 10 deletions

diff --git a/firmware/Makefile b/firmware/Makefile
index 9bf5570..4574e0f 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -18,6 +18,7 @@ CONFIG ?= t85_default
 #     make flash   			# to load the boot loader into flash
 #     make disablereset		# use external reset line for IO (CAUTION: this is not easy to enable again, see README) 
 
+CFLAGS =
 CONFIGPATH	  = configuration/$(CONFIG)
 include $(CONFIGPATH)/Makefile.inc
 
@@ -29,7 +30,7 @@ AVRDUDE = avrdude $(PROGRAMMER) -p $(DEVICE)
 CC = avr-gcc
 
 # Options:
-CFLAGS  = -I. -g2 -Os # -Wall
+CFLAGS += -I. -g2 -Os # -Wall
 CFLAGS += -I$(CONFIGPATH) -mmcu=$(DEVICE) -DF_CPU=$(F_CPU) -DBOOTLOADER_ADDRESS=0x$(BOOTLOADER_ADDRESS) 
 CFLAGS += -nostartfiles -ffunction-sections -fdata-sections -fpack-struct -fno-inline-small-functions -fno-move-loop-invariants -fno-tree-scev-cprop
 
diff --git a/firmware/configuration/t85_aggressive/Makefile.inc b/firmware/configuration/t85_aggressive/Makefile.inc
index 7ac110d..4675ae9 100644
--- a/firmware/configuration/t85_aggressive/Makefile.inc
+++ b/firmware/configuration/t85_aggressive/Makefile.inc
@@ -4,8 +4,16 @@
 
 # Controller type: ATtiny 85
 # Configuration:   Size optimized. Uses 16 MHz V-USB implementation, which may be instable with some computers
-# Last Change:     Mar 16,2014
- 
+# Last Change:     Jan 11,2015
+
+# Enable unsafe optimizions. This will disable several safety features in microncleus to save around 40 more bytes
+# 
+# Disabled features:
+#   * Stack pointer and SREG initialization in CRT
+#   * Client side reset vector patching
+#   * USB collision detection. Micronucleus will not work reliability with hubs if this is disabled.
+
+CFLAGS += -DENABLE_UNSAFE_OPTIMIZATIONS
 
 F_CPU = 16000000
 DEVICE = attiny85
diff --git a/firmware/configuration/t85_default/Makefile.inc b/firmware/configuration/t85_default/Makefile.inc
index 53a4682..ee7252d 100644
--- a/firmware/configuration/t85_default/Makefile.inc
+++ b/firmware/configuration/t85_default/Makefile.inc
@@ -15,7 +15,7 @@ DEVICE = attiny85
 # - for the size of your device (8kb = 1024 * 8 = 8192) subtract above value 2124... = 6068
 # - How many pages in is that? 6068 / 64 (tiny85 page size in bytes) = 94.8125
 # - round that down to 94 - our new bootloader address is 94 * 64 = 6016, in hex = 1780
-BOOTLOADER_ADDRESS = 19C0
+BOOTLOADER_ADDRESS = 1980
 
 FUSEOPT = -U lfuse:w:0xe1:m -U hfuse:w:0xdd:m -U efuse:w:0xfe:m
 FUSEOPT_DISABLERESET = -U lfuse:w:0xe1:m -U efuse:w:0xfe:m -U hfuse:w:0x5d:m
diff --git a/firmware/crt1.S b/firmware/crt1.S
index b018ff1..1f68351 100644
--- a/firmware/crt1.S
+++ b/firmware/crt1.S
@@ -95,11 +95,14 @@ __init:
 
 	.section .init2,"ax",@progbits
 	clr		R1
+    
+#ifndef ENABLE_UNSAFE_OPTIMIZATIONS
 	out		0x3f,r1
 	ldi		r28,lo8(__stack)
 	ldi		r29,hi8(__stack)
 	out		0x3d, r28
 	out		0x3e, r29
+#endif    
 	.section .init9,"ax",@progbits
 ;  rcall main
 ;  XJMP  __vectors-2
diff --git a/firmware/main.c b/firmware/main.c
index 194156c..0cd0d26 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -131,19 +131,21 @@ static inline void writeFlashPage(void) {
 // the device can not be bricked. Saving user-reset-vector is done in the host 
 // tool, starting with firmware V2
 static void writeWordToPageBuffer(uint16_t data) {
-    
-#if BOOTLOADER_ADDRESS < 8192
+
+#ifndef ENABLE_UNSAFE_OPTIMIZATIONS     
+  #if BOOTLOADER_ADDRESS < 8192
   // rjmp
   if (currentAddress.w == RESET_VECTOR_OFFSET * 2) {
     data = 0xC000 + (BOOTLOADER_ADDRESS/2) - 1;
   }
-#else
+  #else
   // far jmp
   if (currentAddress.w == RESET_VECTOR_OFFSET * 2) {
     data = 0x940c;
   } else if (currentAddress.w == (RESET_VECTOR_OFFSET +1 ) * 2) {
     data = (BOOTLOADER_ADDRESS/2);
   }    
+  #endif
 #endif
 
 #if OSCCAL_SAVE_CALIB
@@ -177,7 +179,7 @@ static uint8_t usbFunctionSetup(uint8_t data[8]) {
           command=cmd_write_page; // ask runloop to write our page       
   } else {
     // Handle cmd_erase_application and cmd_exit
-    command=rq->bRequest&0x3f;
+    command=rq->bRequest&0x3f;    
   }
   return 0;
 }
@@ -278,7 +280,7 @@ int main(void) {
         }
         
       } while(--fastctr);     
- 
+      
       wdr();
  
       // commands are only evaluated after next USB transmission or after 5 ms passed
diff --git a/firmware/osccalASM.S b/firmware/osccalASM.S
index fa26dc4..57730bf 100644
--- a/firmware/osccalASM.S
+++ b/firmware/osccalASM.S
@@ -147,6 +147,9 @@ usbCOWaitLoop:
     sbic    USBIN, USBMINUS ;[2] 
     rjmp    usbCOWaitLoop   ;[3]
 
+    ; This section of code deals with traffic from other USB devices on the same hub.
+    ; If this code is excluded, micronucleus may only work when it is connected to a dedicated USB port
+#ifndef ENABLE_UNSAFE_OPTIMIZATIONS
     sbis    USBIN, USBPLUS  ; ignore frame if data is present
     rjmp    usbCOnotdata
 
@@ -161,7 +164,8 @@ usbCOWaitNoData2:
     sbis    USBIN, USBMINUS ; wait for D- go to high
     rjmp    usbCOWaitNoData2
     rjmp    usbCOLoopNoCal
-
+#endif
+    
 usbCOnotdata:
 	sbrs	cnt16H, 7		;delay overflow?
 	rjmp	usbCOclocktoolow