ADD: add codes

README.md

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+riscv64-unknown-elf-gcc.exe -E -o ./main.i ./main.c
+
+riscv64-unknown-elf-gcc.exe -S -o ./main.S ./main.c
+
+riscv64-unknown-elf-gcc.exe -c -o ./main.o ./main.c
+
+
+riscv64-unknown-elf-objdump.exe -h ./main.o
+
+
+riscv64-unknown-elf-gcc.exe -nostdlib -T scratchpad.ld -o ./main.elf ./main.o

main.S

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+	.file	"main.c"
+	.option nopic
+	.attribute arch, "rv64i2p0_m2p0_a2p0_f2p0_d2p0_c2p0"
+	.attribute unaligned_access, 0
+	.attribute stack_align, 16
+	.text
+	.align	1
+	.type	simpleDelay, @function
+simpleDelay:
+	addi	sp,sp,-32
+	sd	s0,24(sp)
+	addi	s0,sp,32
+	sw	zero,-20(s0)
+	j	.L2
+.L3:
+ #APP
+# 16 "./main.c" 1
+	nop
+# 0 "" 2
+ #NO_APP
+	lw	a5,-20(s0)
+	addiw	a5,a5,1
+	sw	a5,-20(s0)
+.L2:
+	lw	a5,-20(s0)
+	sext.w	a4,a5
+	li	a5,999424
+	addi	a5,a5,575
+	ble	a4,a5,.L3
+	nop
+	nop
+	ld	s0,24(sp)
+	addi	sp,sp,32
+	jr	ra
+	.size	simpleDelay, .-simpleDelay
+	.align	1
+	.globl	main
+	.type	main, @function
+main:
+	addi	sp,sp,-16
+	sd	ra,8(sp)
+	sd	s0,0(sp)
+	addi	s0,sp,16
+	li	a5,268500992
+	li	a4,1
+	sw	a4,0(a5)
+.L5:
+	li	a5,268500992
+	lw	a5,0(a5)
+	sext.w	a4,a5
+	li	a5,268500992
+	ori	a4,a4,1
+	sext.w	a4,a4
+	sw	a4,0(a5)
+	call	simpleDelay
+	li	a5,268500992
+	lw	a5,0(a5)
+	sext.w	a4,a5
+	li	a5,268500992
+	andi	a4,a4,-2
+	sext.w	a4,a4
+	sw	a4,0(a5)
+	call	simpleDelay
+	j	.L5
+	.size	main, .-main
+	.ident	"GCC: (SiFive GCC-Metal 10.2.0-2020.12.8) 10.2.0"

main.c

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+#define SET_BITS(REG, BIT)            ((REG) |= (BIT))
+#define CLEAR_BITS(REG, BIT)          ((REG) &= ~(BIT))
+
+#define GPIOA_BASE                    0x10010000U
+
+#define GPIO_PIN_0                    0b0001U
+#define GPIO_PIN_1                    0b0001U
+#define GPIO_PIN_2                    0b0001U
+#define GPIO_PIN_3                    0b0001U
+
+
+
+
+static inline void simpleDelay() {
+  for (int i=0; i<1000000; i+=1) {
+    __asm__("nop");
+  }
+}
+
+int main() {
+  *(unsigned int volatile *)(GPIOA_BASE + 0x00U) = GPIO_PIN_0;
+
+  while (1) {
+    SET_BITS(*(unsigned int volatile *)(GPIOA_BASE + 0x00U), GPIO_PIN_0);
+    simpleDelay();
+
+    CLEAR_BITS(*(unsigned int volatile *)(GPIOA_BASE + 0x00U), GPIO_PIN_0);
+    simpleDelay();
+  }
+}

main.i

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+# 1 "./main.c"
+# 1 "<built-in>"
+# 1 "<command-line>"
+# 1 "./main.c"
+# 14 "./main.c"
+static inline void simpleDelay() {
+  for (int i=0; i<1000000; i+=1) {
+    __asm__("nop");
+  }
+}
+
+int main() {
+  *(unsigned int volatile *)(0x10010000U + 0x00U) = 0b0001U;
+
+  while (1) {
+    ((*(unsigned int volatile *)(0x10010000U + 0x00U)) |= (0b0001U));
+    simpleDelay();
+
+    ((*(unsigned int volatile *)(0x10010000U + 0x00U)) &= ~(0b0001U));
+    simpleDelay();
+  }
+}

scratchpad.ld

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+
+ENTRY(main)
+
+MEMORY {
+  SCRATCHPAD(rwx): ORIGIN = 0x08000000, LENGTH = 4K
+}
+
+SECTIONS {
+  .text : {
+    *(.text)
+  }> SCRATCHPAD
+}