Init

.gitignore

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+bin
+libwrap.a

conf/sdk.mk

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+all: $(TARGET)
+
+MK_FILE_PATH = $(lastword $(MAKEFILE_LIST))
+PRJ_DIR      = $(abspath $(dir $(MK_FILE_PATH)))
+
+# Hardcoded paths
+OPENOCD_BIN	:= /usr/bin/riscv-openocd
+RISCV_SDK_DIR	:= $(abspath $(PRJ_DIR)/../../riscv-sdk)
+OUT_DIR	:= bin
+
+# Variables
+SDK_INC		:= $(RISCV_SDK_DIR)/include
+SDK_WRAP	:= $(RISCV_SDK_DIR)/libwrap
+SDK_OPENOCD_CFG	:= $(RISCV_SDK_DIR)/openocd.cfg
+
+# libwrap config
+include $(SDK_WRAP)/libwrap.mk
+
+# SDK sources
+SDK_SRC_ASM	:= \
+		$(RISCV_SDK_DIR)/entry.S \
+		$(RISCV_SDK_DIR)/start.S
+
+SDK_SRC_C	:= \
+		$(RISCV_SDK_DIR)/init.c
+SDK_LINK_SCRIPT	:= \
+		$(RISCV_SDK_DIR)/flash.lds
+
+# Variable used by libwrap.mk
+INCLUDES	:= -I$(RISCV_SDK_DIR)/include
+
+# Platform specific: HiFive1
+
+#Name of variable required by libwrap.mk
+ARCH_FLAGS	+= \
+		-march=rv32imac -mabi=ilp32 -mcmodel=medany
+
+CFLAGS		+= \
+		-O3 -fno-builtin-printf \
+		-Wall -Wextra -Wshadow -fno-common \
+		$(ARCH_FLAGS) \
+		$(LOCAL_CFLAGS) #-include sys/cdefs.h
+
+LDFLAGS		+= \
+		-static \
+		-L$(RISCV_SDK_DIR) \
+		-T$(SDK_LINK_SCRIPT) \
+		-nostartfiles \
+		--specs=nano.specs \
+		-Wl,--gc-sections \
+		$(LOCAL_LDFLAGS)
+
+# Common targets
+OBJ_S 		:= \
+		$(LOCAL_SRC_S:.S=.o) \
+		$(SDK_SRC_ASM:.S=.o)
+OBJ_C		:= \
+		$(LOCAL_SRC_C:.c=.o) \
+		$(SDK_SRC_C:.c=.o)
+
+# Compilation targets
+$(OBJ_S): %.o: %.S
+	mkdir -p $(OUT_DIR)/$(dir $@)
+	$(CC) $(ARCH_FLAGS) -I$(SDK_INC) $(OPT) -c -o $(OUT_DIR)/$@ $<
+
+$(OBJ_C): %.o: %.c
+	mkdir -p $(OUT_DIR)/$(dir $@)
+	$(CC) -I$(SDK_INC) $(CFLAGS) $(OPT) -c -o $(OUT_DIR)/$@ $<
+
+$(TARGET): $(OBJ_C) $(OBJ_S) $(LIBWRAP)
+	$(CC) -I$(SDK_INC) $(CFLAGS) $(OPT) \
+	$(addprefix $(OUT_DIR)/,$(OBJ_S)) \
+	$(addprefix $(OUT_DIR)/,$(OBJ_C)) \
+	-o $(OUT_DIR)/$@ $(LDFLAGS)
+clean:
+	rm -rf $(OUT_DIR)
+	rm -rf $(LIBWRAP)
+
+run:
+	$(OPENOCD_BIN) -s "sdk" -f $(SDK_OPENOCD_CFG) & \
+	$(GDB) \
+		"$(OUT_DIR)/$(TARGET)" \
+		--batch \
+		-ex "set remotetimeout 240" \
+		-ex "target extended-remote localhost:3333" \
+		-ex "monitor reset halt" \
+		-ex "monitor flash protect 0 64 last off" \
+		-ex "load" \
+		-ex "monitor resume" \
+		-ex "monitor shutdown" \
+		-ex "quit"
+
+.PHONY: clean all run

conf/toolchain.mk

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+# Define toolchain to use
+ARCH 		:= riscv64
+VENDOR		:= unknown
+ABI		:= elf
+BIN_DIR		:= #/usr/local/bin/
+TOOLCHAIN	:= $(BIN_DIR)$(ARCH)-$(VENDOR)-$(ABI)
+
+# Defines compiler and tools to use
+AR		:= $(TOOLCHAIN)-ar
+AS		:= $(TOOLCHAIN)-as
+CC		:= $(TOOLCHAIN)-gcc
+STRIP		:= $(TOOLCHAIN)-strip
+GDB		:= $(TOOLCHAIN)-gdb

cyclecount/Makefile

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+TARGET		:= cyclecount.elf
+LOCAL_SRC_C	:= cyclecount.c
+LOCAL_SRC_S	:= getcycles.S
+LOCAL_OPT_C	:= -Os -fno-builtin-printf -Wall -Wextra -pedantic
+
+include ../conf/toolchain.mk
+include ../conf/sdk.mk

cyclecount/cyclecount.c

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+#include <stdio.h>
+
+uint64_t getcycles();
+static void do_something()
+{
+    for (int i = 0; i < 1000; ++i) {
+        __asm__("NOP");
+    }
+}
+
+int main(void)
+{
+    // Instruction cache misses are relatively expensive, so for more
+    // consistent benchmarks that depend less on the relative speed of
+    // the QSPI flash, you might want to fill the instruction cache first.
+    // Note that it can hold 16 KiB of instructions on the HiFive1.
+    do_something();
+    getcycles();
+    uint64_t oldcount = getcycles();
+    do_something();
+    uint64_t newcount = getcycles();
+
+    printf("That took %d cycles.\n", (unsigned int)(newcount-oldcount));
+    return 0;
+}

cyclecount/getcycles.S

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+.text
+
+.globl getcycles
+.align 2
+getcycles:
+    csrr a1, mcycleh
+    csrr a0, mcycle
+    csrr a2, mcycleh
+    bne a1, a2, getcycles
+    ret