From a48be0b5d74935531bdbd4737dcd15b1ce5282b2 Mon Sep 17 00:00:00 2001
From: Kamila Szewczyk <kspalaiologos@gmail.com>
Date: Tue, 15 Oct 2024 13:32:40 +0200
Subject: [PATCH] aarch64: include feature test in crc32c, add asm unit to
 makefile.

---
 Makefile.am                        |  4 ++++
 configure.ac                       |  9 +++++++++
 crc32c.c                           | 16 +++++++++++++---
 xpar-aarch64.asm => xpar-aarch64.S |  3 ---
 4 files changed, 26 insertions(+), 6 deletions(-)
 rename xpar-aarch64.asm => xpar-aarch64.S (94%)

diff --git a/Makefile.am b/Makefile.am
index ced1432..9206978 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -10,6 +10,10 @@ SUFFIXES = .asm
 	$(NASM) $(NAFLAGS) -o $@ $<
 endif
 
+if XPAR_AARCH64
+xpar_SOURCES += xpar-aarch64.S
+endif
+
 # Developer convenience targets
 .PHONY: update-ChangeLog
 update-ChangeLog:
diff --git a/configure.ac b/configure.ac
index 33d4c41..2e4e773 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,6 +34,15 @@ else
   AM_CONDITIONAL([XPAR_X86_64], [false])
 fi
 
+AC_ARG_ENABLE([aarch64], [AS_HELP_STRING([--enable-aarch64], [Enable aarch64 platform specific code.])], [enable_aarch64=$enableval], [enable_aarch64=no])
+if test "x$enable_aarch64" = "xyes"; then
+  AC_DEFINE([XPAR_AARCH64], [1], [Enable aarch64 platform specific code.])
+  AM_CONDITIONAL([XPAR_AARCH64], [true])
+  AM_PROG_AS
+else
+  AM_CONDITIONAL([XPAR_AARCH64], [false])
+fi
+
 AC_ARG_ENABLE([native], [AS_HELP_STRING([--enable-native], [Enable native platform optimisations.])], [enable_native=$enableval], [enable_native=no])
 if test "x$enable_native" = "xyes"; then
   AX_APPEND_COMPILE_FLAGS([-march=native -mtune=native])
diff --git a/crc32c.c b/crc32c.c
index 047d850..fa1776b 100644
--- a/crc32c.c
+++ b/crc32c.c
@@ -89,26 +89,36 @@ u32 crc32c_tabular(u32 crc, u8 * data, sz length) {
   return crc;
 }
 
+typedef u32 (*crc32c_func)(u32, u8 *, sz);
+
 #if defined(XPAR_X86_64)
   #ifdef HAVE_FUNC_ATTRIBUTE_SYSV_ABI
     #define EXTERNAL_ABI __attribute__((sysv_abi))
   #else
     #define EXTERNAL_ABI
   #endif
-  
-  typedef u32 (*crc32c_func)(u32, u8 *, sz);
+
   extern EXTERNAL_ABI int crc32c_x86_64_cpuflags(void);
   extern EXTERNAL_ABI u32 crc32c_small_x86_64_sse42(u32, u8 *, sz);
+#elif defined(XPAR_AARCH64)
+  extern int crc32c_aarch64_cpuflags(void);
+  extern u32 crc32c_small_aarch64_neon(u32, u8 *, sz);
 #endif
 
 u32 crc32c(u8 * data, sz length) {
-#if defined(XPAR_X86_64)
   static int cpuflags = -1;
+#if defined(XPAR_X86_64)
   if (cpuflags == -1) cpuflags = crc32c_x86_64_cpuflags();
   if (cpuflags & 1)
     return crc32c_small_x86_64_sse42(0xFFFFFFFFL, data, length) ^ 0xFFFFFFFFL;
   else
     return crc32c_tabular(0xFFFFFFFFL, data, length) ^ 0xFFFFFFFFL;
+#elif defined(XPAR_AARCH64)
+  if (cpuflags == -1) cpuflags = crc32c_aarch64_cpuflags();
+  if (cpuflags)
+    return crc32c_small_aarch64_neon(0xFFFFFFFFL, data, length) ^ 0xFFFFFFFFL;
+  else
+    return crc32c_tabular(0xFFFFFFFFL, data, length) ^ 0xFFFFFFFFL;
 #else
   return crc32c_tabular(0xFFFFFFFFL, data, length) ^ 0xFFFFFFFFL;
 #endif
diff --git a/xpar-aarch64.asm b/xpar-aarch64.S
similarity index 94%
rename from xpar-aarch64.asm
rename to xpar-aarch64.S
index 9eb9862..18f524b 100644
--- a/xpar-aarch64.asm
+++ b/xpar-aarch64.S
@@ -12,9 +12,6 @@
   along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
-/* TODO: CPU support checks, merging this into crc32c.c and the build
-         system. Unsure how to do all that right now. */
-
 .section .text
 .extern getauxval