diff --git a/V203/usb/cdc/Makefile b/V203/usb/cdc/Makefile
index 52ddce6..c351225 100644
--- a/V203/usb/cdc/Makefile
+++ b/V203/usb/cdc/Makefile
@@ -1,25 +1,25 @@
+TARGET?= ch32v203
 TOOL  ?= gcc
 #TOOL  ?= clang
-TARGET = ch32v203
 
 PRJ    = example
-VPATH += ./ch32v203
+
+VPATH  = . ./$(TARGET)
 BLD    = ./build/
 DFLAGS = -d
 LFLAGS = -g
 LDLIBS =
 BFLAGS = --strip-unneeded
 
-CFLAGS = -MMD -Wall -Wno-format -Wno-parentheses -ggdb -fno-exceptions -ffunction-sections -fdata-sections
-CFLAGS+= -I. -I./ch32v203
+CFLAGS = -MMD -Wall -Wno-parentheses -ggdb -fno-exceptions -ffunction-sections -fdata-sections
+CFLAGS+= -I. -I./$(TARGET)
 DEL    = rm -f
 
 # zdrojaky
 OBJS   = main.o hack.o print.o
-OBJS  += startup.o system.o usb_desc.o
-OBJS  += cdc_class.o
+OBJS  += usb_desc.o cdc_class.o
 
-include $(TOOL).mk
+include $(TARGET)/$(TOOL).mk
 BOBJS = $(addprefix $(BLD),$(OBJS))
 
 all: $(BLD) $(PRJ).elf
@@ -36,9 +36,6 @@ $(PRJ).elf: $(BOBJS)
 	-@echo "OK."
 	$(COPY) $(BFLAGS) -O binary $(PRJ).elf $(PRJ).bin
 # preloz co je potreba
-$(BLD)%.o: %.S
-	-@echo [AS $(TOOL),$(TARGET)] $@
-	$(AS) -$(CCPU) $< -o $@
 $(BLD)%.o: %.c
 	-@echo [CC $(TOOL),$(TARGET)] $@
 	@$(CC) -std=gnu99 -c $(CFLAGS) $< -o $@
@@ -51,5 +48,5 @@ flash: $(PRJ).elf
 	minichlink -w $(PRJ).bin flash -b
 # vycisti
 clean:
-	$(DEL) $(BLD)* *.lst *.bin *.elf *.map *~ mystrings.inc
+	$(DEL) $(BLD)* *.lst *.bin *.elf *.map *~
 .PHONY: all clean flash run
diff --git a/V203/usb/cdc/clang.mk b/V203/usb/cdc/ch32v203/clang.mk
similarity index 82%
rename from V203/usb/cdc/clang.mk
rename to V203/usb/cdc/ch32v203/clang.mk
index 06e0028..5e3e2b2 100644
--- a/V203/usb/cdc/clang.mk
+++ b/V203/usb/cdc/ch32v203/clang.mk
@@ -6,13 +6,13 @@ LD   = ld.lld
 SIZE = llvm-size
 DUMP = riscv64-unknown-elf-objdump
 COPY = riscv64-unknown-elf-objcopy
-AS   = riscv64-unknown-elf-as
 
-#OBJS  += startup.o system.o
+OBJS  += startup.o system.o
 CCPU   = -march=rv32imac -mabi=ilp32
 MCPU   = $(CCPU)
 TRIP   = riscv32-unknown-none-elf
 CFLAGS+= -Oz
+CFLAGS+= -flto
 CFLAGS+= -fmessage-length=0 -fsigned-char -I/usr/include/newlib
 #CFLAGS+= -fconstexpr-steps=2097152
 CFLAGS+= --target=$(TRIP) $(MCPU)
@@ -20,6 +20,6 @@ LFLAGS+= --Map=$(@:%.elf=%.map) --gc-sections
 # 16-bit instrukce se do toho asi dostanou až na úrovni LLVM linkeru.
 # Bohužel to není nikde pořádně popsáno.
 LFLAGS+= -mllvm -mattr=+c
+LFLAGS+= -lto-O3
 LFLAGS+= -nostdlib
-#LDLIBS+= -L$(SRCDIR)/Ld -T Link.ld
-LDLIBS+= -L./ch32v203 -T script.ld
+LDLIBS+= -L./$(TARGET) -T script.ld
diff --git a/V203/usb/cdc/ch32v203/gcc.mk b/V203/usb/cdc/ch32v203/gcc.mk
new file mode 100644
index 0000000..d2b196c
--- /dev/null
+++ b/V203/usb/cdc/ch32v203/gcc.mk
@@ -0,0 +1,20 @@
+# Use gcc / binutils toolchain
+PREFIX = riscv64-unknown-elf-
+CC  = $(PREFIX)gcc
+CXX = $(PREFIX)g++
+LD   = $(PREFIX)gcc
+SIZE = $(PREFIX)size
+DUMP = $(PREFIX)objdump
+COPY = $(PREFIX)objcopy
+OBJS  += startup.o system.o
+CFLAGS+= -Os
+CFLAGS+= -flto
+CCPU   = -march=rv32imac -mabi=ilp32
+MCPU   = $(CCPU)
+
+CFLAGS+= $(MCPU) -msmall-data-limit=8 -mno-save-restore -fmessage-length=0 -fsigned-char -I/usr/include/newlib
+LFLAGS+= -Wl,--Map=$(@:%.elf=%.map),--gc-sections
+#LFLAGS+= -Wl,--print-sysroot -- chyba ld ?
+LFLAGS+= -flto
+LFLAGS+= -Os $(MCPU) -nostartfiles -nostdlib
+LDLIBS+= -lgcc -L./$(TARGET) -T script.ld
diff --git a/V203/usb/cdc/ch32v203/script.ld b/V203/usb/cdc/ch32v203/script.ld
index ff0035b..79eb3dc 100644
--- a/V203/usb/cdc/ch32v203/script.ld
+++ b/V203/usb/cdc/ch32v203/script.ld
@@ -1,4 +1,4 @@
-ENTRY( Init )
+ENTRY( InterruptVector )
 MEMORY
 {
   FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 64K
diff --git a/V203/usb/cdc/gcc.mk b/V203/usb/cdc/gcc.mk
deleted file mode 100644
index b318671..0000000
--- a/V203/usb/cdc/gcc.mk
+++ /dev/null
@@ -1,21 +0,0 @@
-# Use gcc / binutils toolchain
-PREFIX = riscv64-unknown-elf-
-CC  = $(PREFIX)gcc
-CXX = $(PREFIX)g++
-LD   = $(PREFIX)gcc
-AS   = $(PREFIX)as
-SIZE = $(PREFIX)size
-DUMP = $(PREFIX)objdump
-COPY = $(PREFIX)objcopy
-#OBJS  += startup.o system.o
-CFLAGS+= -Os
-CCPU   = -march=rv32imac -mabi=ilp32
-MCPU   = $(CCPU)
-
-CFLAGS+= $(MCPU) -fmessage-length=0 -I/usr/include/newlib
-LFLAGS+= -Wl,--Map=$(@:%.elf=%.map),--gc-sections
-#LFLAGS+= -Wl,--print-sysroot -- chyba ld ?
-LFLAGS+= -O3 $(MCPU) -nostartfiles -nostdlib
-#LFLAGS+= -L${HOME}/Downloads/MRS_Toolchain_Linux_x64_V1.91/RISC-V_Embedded_GCC/riscv-none-embed/lib/rv32imac/ilp32 -lprintf -lc
-#LDLIBS+= -L$(SRCDIR)/Ld -T Link.ld
-LDLIBS+= -L./ch32v203 -T script.ld