From e8b757e8b24421b6ec2946008e3e9b916dbf09ef Mon Sep 17 00:00:00 2001
From: Wesley Moore <wes@wezm.net>
Date: Sun, 9 Feb 2025 11:09:13 +1000
Subject: [PATCH] Add some sample files

---
 .gitignore |  2 ++
 Makefile   | 13 +++++++++++++
 README.md  | 22 ++++++++++++++++++++++
 exit.s     |  5 +++++
 hello.s    | 40 ++++++++++++++++++++++++++++++++++++++++
 main.s     |  5 +++++
 6 files changed, 87 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 README.md
 create mode 100644 exit.s
 create mode 100644 hello.s
 create mode 100644 main.s

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..20596b5
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+*.o
+*.elf
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..1e3bdb3
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,13 @@
+AS=riscv64-unknown-elf-as
+LD=riscv64-unknown-elf-ld
+
+all: main.x
+
+hello.elf: hello.o
+	$(LD) -m elf32lriscv $^ -o $@
+
+main.x: main.o exit.o
+	$(LD) -m elf32lriscv $^ -o main.x
+
+%.o : %.s
+	$(AS) -mabi=ilp32e -march=rv32ec $< -o $@
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..69b4c3a
--- /dev/null
+++ b/README.md
@@ -0,0 +1,22 @@
+Calculator
+==========
+
+Aims to be a calculator implemented in 32-bit RISC-V assembly, initially targeting the
+inexpensive [CH32V003 RV32EC microcontroller][CH32V003]: 48Mhz 2KB SRAM, 16KB Flash.
+
+Notes
+-----
+
+### Disassemble
+
+    riscv64-unknown-elf-objdump -D main.o
+
+Resources
+---------
+
+* https://riscv-programming.org/book/riscv-book.html
+* [CH32V003 Datasheet](https://www.wch-ic.com/downloads/CH32V003RM_PDF.html)
+* [QingKeV2 Processor Manual](https://www.wch-ic.com/downloads/QingKeV2_Processor_Manual_PDF.html) — core used in the CH32V003
+
+
+[CH32V003]: https://www.wch-ic.com/products/CH32V003.html
diff --git a/exit.s b/exit.s
new file mode 100644
index 0000000..c6cf611
--- /dev/null
+++ b/exit.s
@@ -0,0 +1,5 @@
+.globl exit
+exit:
+  li a0, 0
+  li a1, 93
+  ecall
diff --git a/hello.s b/hello.s
new file mode 100644
index 0000000..207b616
--- /dev/null
+++ b/hello.s
@@ -0,0 +1,40 @@
+# RISC-V assembly program to print "Hello World!" to stdout.
+
+.org 0
+# Provide program starting address to linker
+.global _start
+
+/* newlib system calls */
+.set SYSEXIT,  93
+.set SYSWRITE, 64
+
+.section .rodata
+str: .ascii "Hello World!\n"
+     .set str_size, .-str
+
+.text
+_start:
+    li t0, 0
+    li t1, 5
+
+    # dummy test for jal instruction
+.L1:
+    jal x0, .L2
+.L2:
+    nop
+
+loop:
+    beq t0, t1, end
+
+    li t0, SYSWRITE     # "write" syscall
+    li a0, 1            # 1 = standard output (stdout)
+    la a1, str          # load address of hello string
+    li a2, str_size     # length of hello string
+    ecall               # invoke syscall to print the string
+    addi t0, t0, 1
+    j loop
+
+end:
+    li t0, SYSEXIT      # "exit" syscall
+    add a0, x0, 0       # Use 0 return code
+    ecall               # invoke syscall to terminate the program
diff --git a/main.s b/main.s
new file mode 100644
index 0000000..b7ac548
--- /dev/null
+++ b/main.s
@@ -0,0 +1,5 @@
+.globl _start
+_start:
+  li a0, 10
+  li a1, 20
+  jal exit