first commit

rv_tests/hello_world/hello.S

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+.section .text.init
+.global _start
+
+.equ UART_BASE, 0x10000000  # QEMU's UART base address
+
+_start:
+    # Load address of the string into a1
+    la a1, message
+
+loop:
+    lbu a0, 0(a1)            # Load a byte from the string
+    beqz a0, exit            # If null terminator, exit
+    li t0, UART_BASE         # Load UART address
+    sb a0, 0(t0)             # Store character to UART (8-bit write)
+    addi a1, a1, 1           # Move to next character
+    j loop                   # Repeat
+
+exit:
+    j exit                   # Infinite loop
+
+.section .rodata
+message:
+    .asciz "Hello, world!\n"