1 files changed, 65 insertions, 0 deletions
diff --git a/2021/asm/day01.asm b/2021/asm/day01.asm
new file mode 100644
index 0000000..b4f73e7
--- /dev/null
+++ b/2021/asm/day01.asm
@@ -0,0 +1,65 @@
+%include "unistd.asm"
+%include "utils.asm"
+
+stdout equ 1
+
+global _start
+
+section .text
+_start:
+    mov     rcx, [rsp]              ; Get number of arguments
+    mov     rdi, [rsp + rcx * 8]    ; Get last argument
+
+    mov     rax, SYS_access         ; Check if file exists and is readable
+    mov     esi, R_OK
+    syscall
+    test    rax, rax
+    jnz     .exit_err
+
+    mov     rax, SYS_open
+    xor     esi, esi
+    xor     edx, edx
+    syscall
+
+    mov     r8d, eax                ; Move fd into r8
+    mov     rax, SYS_mmap
+    xor     edi, edi                ; Let the kernel choose the address
+    mov     rsi, 12288
+    mov     rdx, PROT_READ
+    mov     r10d, MAP_PRIVATE
+    xor     r9d, r9d
+    syscall
+
+    cmp     rax, -1                 ; Exit on error
+    je      .exit_err
+
+    xor     r13d, r13d
+    mov     r12d, ~0
+    mov     rdi, rax
+.loop:
+    call    atoi
+    cmp     eax, r12d
+    jna     .na
+    inc     r13d
+.na:
+    mov     r12d, eax
+
+    cmp     byte [rdi], 0
+    je     .exit
+    inc     rdi
+    cmp     byte [rdi], 0
+    jne     .loop
+
+.exit:
+    mov     edi, stdout
+    mov     esi, r13d
+    call    write_ulong
+
+    mov     rax, SYS_exit
+    xor     edi, edi
+    syscall
+
+.exit_err:
+    mov     rax, SYS_exit
+    mov     edi, 1
+    syscall