encoding.binary: add _fixed variants for the conversion fns, that accept fixed arrays (#20766)

vlib/encoding/binary/little_endian_fixed.v

@@ -0,0 +1,51 @@
+// Copyright (c) 2019-2024 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+module binary
+
+// little_endian_u16_fixed creates a u16 from the fixed array b in little endian order.
+@[direct_array_access; inline]
+pub fn little_endian_u16_fixed(b [2]u8) u16 {
+	return u16(b[0]) | (u16(b[1]) << u16(8))
+}
+
+// little_endian_put_u16_fixed writes a u16 to the fixed array b in little endian order.
+@[direct_array_access; inline]
+pub fn little_endian_put_u16_fixed(mut b [2]u8, v u16) {
+	b[0] = u8(v)
+	b[1] = u8(v >> u16(8))
+}
+
+// little_endian_u32_fixed creates a u32 from the fixed array b in little endian order.
+@[direct_array_access; inline]
+pub fn little_endian_u32_fixed(b [4]u8) u32 {
+	return u32(b[0]) | (u32(b[1]) << u32(8)) | (u32(b[2]) << u32(16)) | (u32(b[3]) << u32(24))
+}
+
+// little_endian_put_u32_fixed writes a u32 to the fixed array b in little endian order.
+@[direct_array_access; inline]
+pub fn little_endian_put_u32_fixed(mut b [4]u8, v u32) {
+	b[0] = u8(v)
+	b[1] = u8(v >> u32(8))
+	b[2] = u8(v >> u32(16))
+	b[3] = u8(v >> u32(24))
+}
+
+// little_endian_u64_fixed creates a u64 from the fixed array b in little endian order.
+@[direct_array_access; inline]
+pub fn little_endian_u64_fixed(b [8]u8) u64 {
+	return u64(b[0]) | (u64(b[1]) << u64(8)) | (u64(b[2]) << u64(16)) | (u64(b[3]) << u64(24)) | (u64(b[4]) << u64(32)) | (u64(b[5]) << u64(40)) | (u64(b[6]) << u64(48)) | (u64(b[7]) << u64(56))
+}
+
+// little_endian_put_u64_fixed writes a u64 to the fixed array b in little endian order.
+@[direct_array_access; inline]
+pub fn little_endian_put_u64_fixed(mut b [8]u8, v u64) {
+	b[0] = u8(v)
+	b[1] = u8(v >> u64(8))
+	b[2] = u8(v >> u64(16))
+	b[3] = u8(v >> u64(24))
+	b[4] = u8(v >> u64(32))
+	b[5] = u8(v >> u64(40))
+	b[6] = u8(v >> u64(48))
+	b[7] = u8(v >> u64(56))
+}