[PATCH v4 1/8] arg_parser: new library for command line parsing

[Euan Bourke <euan.bourke@intel.com>]

Add a new library to make it easier for eal and other libraries to parse
command line arguments.

The first function in this library is one to parse a corelist string
into an array of individual core ids. The function will then return the
total number of cores described in the corelist.

Signed-off-by: Euan Bourke <euan.bourke@intel.com>
---
 .mailmap                        |   1 +
 MAINTAINERS                     |   4 ++
 doc/api/doxy-api-index.md       |   1 +
 doc/api/doxy-api.conf.in        |   1 +
 lib/arg_parser/arg_parser.c     | 108 ++++++++++++++++++++++++++++++++
 lib/arg_parser/meson.build      |   7 +++
 lib/arg_parser/rte_arg_parser.h |  66 +++++++++++++++++++
 lib/arg_parser/version.map      |  10 +++
 lib/meson.build                 |   2 +
 9 files changed, 200 insertions(+)
 create mode 100644 lib/arg_parser/arg_parser.c
 create mode 100644 lib/arg_parser/meson.build
 create mode 100644 lib/arg_parser/rte_arg_parser.h
 create mode 100644 lib/arg_parser/version.map

diff --git a/.mailmap b/.mailmap
index ab0742a382..528bc68a30 100644
--- a/.mailmap
+++ b/.mailmap
@@ -379,6 +379,7 @@ Eric Zhang <eric.zhang@windriver.com>
 Erik Gabriel Carrillo <erik.g.carrillo@intel.com>
 Erik Ziegenbalg <eziegenb@brocade.com>
 Erlu Chen <erlu.chen@intel.com>
+Euan Bourke <euan.bourke@intel.com>
 Eugenio Pérez <eperezma@redhat.com>
 Eugeny Parshutin <eugeny.parshutin@linux.intel.com>
 Evan Swanson <evan.swanson@intel.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 0d1c8126e3..68ef5ba14b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1756,6 +1756,10 @@ M: Nithin Dabilpuram <ndabilpuram@marvell.com>
 M: Pavan Nikhilesh <pbhagavatula@marvell.com>
 F: lib/node/
 
+Argument parsing
+M: Bruce Richardson <bruce.richardson@intel.com>
+F: lib/arg_parser/
+
 
 Test Applications
 -----------------
diff --git a/doc/api/doxy-api-index.md b/doc/api/doxy-api-index.md
index a6a768bd7c..743d3b6773 100644
--- a/doc/api/doxy-api-index.md
+++ b/doc/api/doxy-api-index.md
@@ -215,6 +215,7 @@ The public API headers are grouped by topics:
     [udp4_input_node](@ref rte_node_udp4_input_api.h)
 
 - **basic**:
+  [argument parsing](@ref rte_arg_parser.h),
   [bitops](@ref rte_bitops.h),
   [approx fraction](@ref rte_approx.h),
   [random](@ref rte_random.h),
diff --git a/doc/api/doxy-api.conf.in b/doc/api/doxy-api.conf.in
index e94c9e4e46..05718ba6ed 100644
--- a/doc/api/doxy-api.conf.in
+++ b/doc/api/doxy-api.conf.in
@@ -28,6 +28,7 @@ INPUT                   = @TOPDIR@/doc/api/doxy-api-index.md \
                           @TOPDIR@/lib/eal/include \
                           @TOPDIR@/lib/eal/include/generic \
                           @TOPDIR@/lib/acl \
+                          @TOPDIR@/lib/arg_parser \
                           @TOPDIR@/lib/bbdev \
                           @TOPDIR@/lib/bitratestats \
                           @TOPDIR@/lib/bpf \
diff --git a/lib/arg_parser/arg_parser.c b/lib/arg_parser/arg_parser.c
new file mode 100644
index 0000000000..d8324a27b1
--- /dev/null
+++ b/lib/arg_parser/arg_parser.c
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2023 Intel Corporation
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include <stdbool.h>
+
+#include <rte_arg_parser.h>
+#include <rte_common.h>
+
+
+struct core_bits {
+	uint8_t bits[(UINT16_MAX + 1) / CHAR_BIT];
+	uint16_t max_bit_set;
+	uint16_t min_bit_set;
+	uint32_t total_bits_set;
+};
+
+static inline bool
+get_core_bit(struct core_bits *mask, uint16_t idx)
+{
+	return !!(mask->bits[idx / CHAR_BIT] & (1 << (idx % CHAR_BIT)));
+}
+
+static inline void
+set_core_bit(struct core_bits *mask, uint16_t idx)
+{
+	if (get_core_bit(mask, idx))
+		return;
+
+	mask->bits[idx / CHAR_BIT] |= 1 << (idx % CHAR_BIT);
+	/* Update min and max bit if its first time setting a bit */
+	if (++(mask->total_bits_set) == 1) {
+		mask->min_bit_set = idx;
+		mask->max_bit_set = idx;
+		return;
+	}
+
+	if (idx > mask->max_bit_set)
+		mask->max_bit_set = idx;
+
+	if (idx < mask->min_bit_set)
+		mask->min_bit_set = idx;
+}
+
+static inline uint32_t
+corebits_to_array(struct core_bits *mask, uint16_t *cores, size_t max_cores)
+{
+	uint32_t count = 0;
+	for (uint32_t i = mask->min_bit_set; i <= mask->max_bit_set && count < max_cores; i++) {
+		if (get_core_bit(mask, i))
+			cores[count++] = i;
+	}
+	return mask->total_bits_set;
+}
+
+
+int
+rte_arg_parse_corelist(const char *corelist, uint16_t *cores, uint32_t cores_len)
+{
+	struct core_bits mask = {0};
+	int32_t min = -1;
+	char *end = NULL;
+
+	min = -1;
+	do {
+		int64_t idx;
+		int32_t max;
+
+		while (isblank(*corelist))
+			corelist++;
+		if (!isdigit(*corelist))
+			return -EINVAL;
+
+		errno = 0;
+		idx = strtol(corelist, &end, 10);
+		if (errno || end == NULL || idx > UINT16_MAX)
+			return -EINVAL;
+		while (isblank(*end))
+			end++;
+		if (*end == '-')
+			min = idx;
+
+		else if (*end == ',' || *end == '\0') {
+			/* Check for first number in range */
+			if (min == -1)
+				min = max = idx;
+			/* Swap if min is larger than max */
+			else if (min > idx) {
+				max = min;
+				min = idx;
+			} else /* Normal case */
+				max = idx;
+
+			for (; min <= max; min++)
+				set_core_bit(&mask, min);
+
+			min = -1;
+		} else
+			return -EINVAL;
+		corelist = end + 1;
+	} while (*end != '\0');
+
+	return corebits_to_array(&mask, cores, cores_len);
+}
diff --git a/lib/arg_parser/meson.build b/lib/arg_parser/meson.build
new file mode 100644
index 0000000000..6ee228bd69
--- /dev/null
+++ b/lib/arg_parser/meson.build
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2023 Intel Corporation
+
+sources = files('arg_parser.c')
+headers = files('rte_arg_parser.h')
+
+includes += global_inc
diff --git a/lib/arg_parser/rte_arg_parser.h b/lib/arg_parser/rte_arg_parser.h
new file mode 100644
index 0000000000..a1ef428b95
--- /dev/null
+++ b/lib/arg_parser/rte_arg_parser.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2023 Intel Corporation
+ */
+
+#ifndef _RTE_ARG_PARSER_H_
+#define _RTE_ARG_PARSER_H_
+
+/**
+ * @file
+ *
+ * RTE Argument Parsing API
+ *
+ * The argument parsing API is a collection of functions to help parse
+ * command line arguments. The API takes a string input and will return
+ * it to the user in a more usable format.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+
+#include <rte_compat.h>
+
+
+/**
+ * Convert a string describing a list of core ids into an array of core ids.
+ *
+ * On success, the passed array is filled with the core ids present in the list up
+ * to the "cores_len", and the number of unique cores present in the "corelist"
+ * is returned.
+ * For example, passing a 1-3,6 "corelist" results in an array of [1, 2, 3, 6]
+ * and would return 4.
+ *
+ * NOTE: if the length of the input array is insufficient to hold the number of core ids
+ * in "corelist" the input array is filled to capacity but the return value is the
+ * number of elements which would have been written to the array, had enough space been
+ * available. [This is similar to the behaviour of the snprintf function]. Because of
+ * this, the number of core values in the "corelist" may be determined by calling the
+ * function with a NULL array pointer and array length given as 0.
+ *
+ * @param corelist
+ *   Input string describing a list of core ids.
+ * @param cores
+ *   An array where to store the core ids.
+ *   Array can be NULL if "cores_len" is 0.
+ * @param cores_len
+ *   The length of the "cores" array.
+ *   If the size is smaller than that needed to hold all cores from "corelist",
+ *   only "cores_len" elements will be written to the array.
+ * @return
+ *   n: the number of unique cores present in "corelist".
+ *   -EINVAL if the string was invalid.
+ *   NOTE: if n > "cores_len", then only "cores_len" elements in the "cores" array are valid.
+ */
+__rte_experimental
+int
+rte_arg_parse_corelist(const char *corelist, uint16_t *cores, uint32_t cores_len);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _RTE_ARG_PARSER_H_ */
diff --git a/lib/arg_parser/version.map b/lib/arg_parser/version.map
new file mode 100644
index 0000000000..b0caaac569
--- /dev/null
+++ b/lib/arg_parser/version.map
@@ -0,0 +1,10 @@
+DPDK_24 {
+	local: *;
+};
+
+EXPERIMENTAL {
+	global:
+
+	# added in 24.03
+	rte_arg_parse_corelist;
+};
diff --git a/lib/meson.build b/lib/meson.build
index 6c143ce5a6..db9e769033 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -11,6 +11,7 @@
 libraries = [
         'log',
         'kvargs', # eal depends on kvargs
+        'arg_parser',
         'telemetry', # basic info querying
         'eal', # everything depends on eal
         'ring',
@@ -72,6 +73,7 @@ if is_ms_compiler
             'log',
             'kvargs',
             'telemetry',
+            'arg_parser',
     ]
 endif
 
-- 
2.34.1