From 959891e33f61ab8d0590e736198bf48e48d2105c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Ol=C5=A1=C3=A1k?= <marek.olsak@amd.com>
Date: Mon, 25 Mar 2024 02:27:01 -0400
Subject: [PATCH] util: add new format helpers

we'll use them

Reviewed-by: Yonggang Luo <luoyonggang@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28733>
---
 src/util/format/u_format.c | 52 ++++++++++++++++++++++++++++++++++++++
 src/util/format/u_format.h |  4 +++
 2 files changed, 56 insertions(+)

diff --git a/src/util/format/u_format.c b/src/util/format/u_format.c
index 30dd65e8428..afcf781d294 100644
--- a/src/util/format/u_format.c
+++ b/src/util/format/u_format.c
@@ -1468,3 +1468,55 @@ util_format_get_array(const enum util_format_type type, const unsigned bits,
 
    return PIPE_FORMAT_NONE;
 }
+
+unsigned
+util_format_get_last_component(enum pipe_format format)
+{
+   const struct util_format_description *desc = util_format_description(format);
+   unsigned num = 0;
+
+   for (unsigned i = 1; i < 4; i++) {
+      if (desc->swizzle[i] <= PIPE_SWIZZLE_W)
+         num = i;
+   }
+   return num;
+}
+
+int
+util_format_get_largest_non_void_channel(enum pipe_format format)
+{
+   const struct util_format_description *desc = util_format_description(format);
+   int chan = -1, max_size = 0;
+
+   for (int i = 0; i < 4; i++) {
+      if (desc->channel[i].type != UTIL_FORMAT_TYPE_VOID &&
+          desc->channel[i].size > max_size) {
+         chan = i;
+         max_size = desc->channel[i].size;
+      }
+   }
+
+   return chan;
+}
+
+unsigned
+util_format_get_max_channel_size(enum pipe_format format)
+{
+   const struct util_format_description *desc = util_format_description(format);
+   int max_src_chan = util_format_get_largest_non_void_channel(format);
+   assert(max_src_chan >= 0 || util_format_is_compressed(format));
+
+   switch (format) {
+   case PIPE_FORMAT_BPTC_RGB_FLOAT:
+   case PIPE_FORMAT_BPTC_RGB_UFLOAT:
+      return 16;
+   case PIPE_FORMAT_ETC2_R11_UNORM:
+   case PIPE_FORMAT_ETC2_R11_SNORM:
+   case PIPE_FORMAT_ETC2_RG11_UNORM:
+   case PIPE_FORMAT_ETC2_RG11_SNORM:
+      return 11;
+   default:
+      return util_format_is_compressed(format) ?
+               8 : desc->channel[max_src_chan].size;
+   }
+}
diff --git a/src/util/format/u_format.h b/src/util/format/u_format.h
index 00d3e75e5a0..d19b3111b3a 100644
--- a/src/util/format/u_format.h
+++ b/src/util/format/u_format.h
@@ -1797,6 +1797,10 @@ util_format_get_array(const enum util_format_type type, const unsigned bits,
                       const unsigned nr_components, const bool normalized,
                       const bool pure_integer);
 
+unsigned util_format_get_last_component(enum pipe_format format);
+int util_format_get_largest_non_void_channel(enum pipe_format format);
+unsigned util_format_get_max_channel_size(enum pipe_format format);
+
 #ifdef __cplusplus
 } // extern "C" {
 #endif