Complete single file cat

src/file.S

@@ -0,0 +1,38 @@
+.data
+cat_buf:    .space 4096
+
+.section .text
+.globl cat_file
+
+# Fetch argument count
+# @param[in] a0: ptr to null-terminated file str.
+# @param[out] a0: result code.
+cat_file:
+    mv a1, a0 # since the function takes in a0, move it to a1 for syscall
+    
+    li a0, -100 # relative/absolute path
+    li a2, 0 # readonly
+    li a7, 56 # open
+    ecall
+
+    mv t0, a0 # put fd in t0
+
+    1:
+    mv a0, t0
+    la a1, cat_buf
+    li a2, 4096
+    li a7, 63
+    ecall
+    blez a0, 2f
+    mv a2, a0 # move bytes read into bytes needed to write
+
+    li a0, 1
+    la a1, cat_buf
+    li a7, 64
+    ecall
+    j 1b
+    
+    2:
+    ret
+
+