[PATCH v2 2/2] lpm: add a scalar version of lookupx4 function

[Stanislaw Kardach <kda@semihalf.com>]

From: Michal Mazurek <maz@semihalf.com>

Add an implementation of the rte_lpm_lookupx4() function for platforms
without support for vector operations.

This will be useful in the upcoming RISC-V port as well as any platform
which may want to start with a basic level of LPM support.

Signed-off-by: Michal Mazurek <maz@semihalf.com>
Signed-off-by: Stanislaw Kardach <kda@semihalf.com>
---
 doc/guides/rel_notes/release_22_07.rst |  5 ++++
 lib/lpm/meson.build                    |  1 +
 lib/lpm/rte_lpm.h                      |  4 ++-
 lib/lpm/rte_lpm_scalar.h               | 36 ++++++++++++++++++++++++++
 4 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 lib/lpm/rte_lpm_scalar.h

diff --git a/doc/guides/rel_notes/release_22_07.rst b/doc/guides/rel_notes/release_22_07.rst
index e49cacecef..0cf3f71269 100644
--- a/doc/guides/rel_notes/release_22_07.rst
+++ b/doc/guides/rel_notes/release_22_07.rst
@@ -104,6 +104,11 @@ New Features
   * ``RTE_EVENT_QUEUE_ATTR_WEIGHT``
   * ``RTE_EVENT_QUEUE_ATTR_AFFINITY``
 
+* **Added scalar version of the LPM library.**
+
+  * Added scalar implementation of ``rte_lpm_lookupx4``. This is a fall-back
+    implementation for platforms that don't support vector operations.
+
 
 Removed Items
 -------------
diff --git a/lib/lpm/meson.build b/lib/lpm/meson.build
index 78d91d3421..6b47361fce 100644
--- a/lib/lpm/meson.build
+++ b/lib/lpm/meson.build
@@ -14,6 +14,7 @@ headers = files('rte_lpm.h', 'rte_lpm6.h')
 indirect_headers += files(
         'rte_lpm_altivec.h',
         'rte_lpm_neon.h',
+        'rte_lpm_scalar.h',
         'rte_lpm_sse.h',
         'rte_lpm_sve.h',
 )
diff --git a/lib/lpm/rte_lpm.h b/lib/lpm/rte_lpm.h
index 1cf863a146..4f38864fde 100644
--- a/lib/lpm/rte_lpm.h
+++ b/lib/lpm/rte_lpm.h
@@ -405,8 +405,10 @@ rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
 #endif
 #elif defined(RTE_ARCH_PPC_64)
 #include "rte_lpm_altivec.h"
-#else
+#elif defined(RTE_ARCH_X86)
 #include "rte_lpm_sse.h"
+#else
+#include "rte_lpm_scalar.h"
 #endif
 
 #ifdef __cplusplus
diff --git a/lib/lpm/rte_lpm_scalar.h b/lib/lpm/rte_lpm_scalar.h
new file mode 100644
index 0000000000..2fc0e19161
--- /dev/null
+++ b/lib/lpm/rte_lpm_scalar.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2022 StarFive
+ * Copyright(c) 2022 SiFive
+ * Copyright(c) 2022 Semihalf
+ */
+
+#ifndef _RTE_LPM_SCALAR_H_
+#define _RTE_LPM_SCALAR_H_
+
+#include <rte_branch_prediction.h>
+#include <rte_byteorder.h>
+#include <rte_common.h>
+#include <rte_vect.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static inline void
+rte_lpm_lookupx4(const struct rte_lpm *lpm, xmm_t ip, uint32_t hop[4],
+		uint32_t defv)
+{
+	uint32_t nh;
+	int i, ret;
+
+	for (i = 0; i < 4; i++) {
+		ret = rte_lpm_lookup(lpm, ((rte_xmm_t)ip).u32[i], &nh);
+		hop[i] = (ret == 0) ? nh : defv;
+	}
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_LPM_SCALAR_H_ */
-- 
2.30.2