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[nyax.git] / stage3 / memory.asm

diff --git a/stage3/memory.asm b/stage3/memory.asm
new file mode 100644 (file)
index 0000000..b4410a3
--- /dev/null
+++ b/stage3/memory.asm
@@ -0,0 +1,59 @@
+global memcpy, memmove
+
+section .text
+
+memcpy:
+.bulk_copy:
+       cmp rdx, 8
+       jl .bytewise_copy
+       mov rax, qword[rsi]
+       mov qword[rdi], rax
+       sub rdx, 8
+       add rdi, 8
+       add rsi, 8
+.bytewise_copy:
+       cmp rdx, 0
+       je .return
+       mov al, byte[rsi]
+       mov byte[rdi], al
+       dec rdx
+       inc rdi
+       inc rsi
+       jmp .bytewise_copy
+.return:
+       ret
+
+memmove:
+       mov rcx, rdx
+.bulk_read:
+       cmp rdx, 8
+       jl .bytewise_read
+       push qword[rsi]
+       add rsi, 8
+       sub rdx, 8
+       jmp .bulk_read
+.bytewise_read:
+       cmp rdx, 0
+       je .bulk_write
+       dec rsp
+       mov al, byte[rsi]
+       mov byte[rsp], al
+       inc rsi
+       dec rdx
+       jmp .bytewise_read
+.bulk_write:
+       cmp rcx, 8
+       jl .bytewise_write
+       pop qword[rdi]
+       add rdi, 8
+       sub rcx, 8
+.bytewise_write:
+       cmp rcx, 0
+       je .return
+       mov al, byte[rsp]
+       mov byte[rdi], al
+       inc rsp
+       inc rdi
+       dec rcx
+.return:
+       ret