From 8c644dd120c63244f4b576b45cd4ae96842736f8 Mon Sep 17 00:00:00 2001
From: quou <quou@disroot.org>
Date: Sun, 9 Feb 2025 18:49:00 +1100
Subject: support for structured buffers

---
 sc/sc.cpp | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 1 deletion(-)

(limited to 'sc')

diff --git a/sc/sc.cpp b/sc/sc.cpp
index 143c408..9b1789f 100644
--- a/sc/sc.cpp
+++ b/sc/sc.cpp
@@ -206,6 +206,10 @@ struct Desc {
 		std::string strct;
 		std::unordered_map<std::string, int> offsets;
 	};
+	struct SBuffer {
+		int stage;
+		std::string strct;
+	};
 	int type;
 	std::vector<Binding> bindings;
 	std::vector<Variable> trgts;
@@ -213,6 +217,7 @@ struct Desc {
 	std::unordered_map<std::string, Struct> structs;
 	std::unordered_map<std::string, Texture> textures;
 	std::unordered_map<std::string, CBuffer> cbuffers;
+	std::unordered_map<std::string, SBuffer> sbuffers;
 	std::vector<Descriptor> descriptors;
 	std::string entrypoints[shader_type_count];
 	void read_var(Variable& d, cfg_Object* desc) {
@@ -297,6 +302,7 @@ struct Desc {
 		}
 		desc = desc->next;
 		Struct& s = structs[n];
+		s.name = n;
 		while (desc && !strcmp(desc->name, "variable")) {
 			Variable v;
 			read_var(v, desc);
@@ -344,6 +350,36 @@ struct Desc {
 		buf.size = offset;
 	}
 
+	void read_sbuffer(cfg_Object* desc) {
+		const char* sname = find_string_default(desc, "name", 0);
+		if (!sname) {
+			print_err("%s must have a name.\n", desc->name);
+			pbreak(951);
+		}
+		const char* stype = find_string_default(desc, "type", 0);
+		if (!stype) {
+			print_err("%s must define a type.\n", desc->name);
+		}
+		std::string n = std::string(sname);
+		std::string t = std::string(stype);
+		if (n.size() > 23) {
+			print_err("SBuffer name too long (max 23 chars).\n");
+			pbreak(952);
+		}
+		if (!structs.contains(t)) {
+			print_err("No such struct %s\n", stype);
+			pbreak(953);
+		}
+		const char* sstage = find_string_default(desc, "stage", 0);
+		if (!sstage) {
+			print_err("%s must define a stage.\n", sname);
+			pbreak(954);
+		}
+		SBuffer& buf = sbuffers[n];
+		buf.strct = t;
+		buf.stage |= 1 << stage_from_string(sstage);
+	}
+
 	void build(cfg_Object* desc) {
 		int i;
 		Binding* cur_binding = 0;
@@ -392,6 +428,8 @@ struct Desc {
 				read_texture(desc);
 			} else if (!strcmp(desc->name, "cbuffer")) {
 				read_cbuffer(desc);
+			} else if (!strcmp(desc->name, "sbuffer")) {
+				read_sbuffer(desc);
 			} else if (!strcmp(desc->name, "struct")) {
 				desc = read_struct(desc);
 				continue;
@@ -417,7 +455,11 @@ struct Desc {
 
 	void build_descriptors() {
 		int slot = 0;
-		descriptors.resize(textures.size() + cbuffers.size());
+		descriptors.resize(
+			textures.size() +
+			cbuffers.size() +
+			sbuffers.size()
+		);
 		for (auto& i : textures) {
 			Descriptor* d = find_desc(i.first.c_str());
 			d->name = i.first;
@@ -432,6 +474,13 @@ struct Desc {
 			d->stage = i.second.stage;
 			slot++;
 		}
+		for (auto& i : sbuffers) {
+			Descriptor* d = find_desc(i.first.c_str());
+			d->name = i.first;
+			d->slot = slot;
+			d->stage = i.second.stage;
+			slot++;
+		}
 	}
 
 	void add_textures(std::stringstream& ss, Shader_Type stage) {
@@ -468,6 +517,40 @@ struct Desc {
 		}
 	}
 
+	void add_sbuffer_structs(std::stringstream& ss, Shader_Type stage) {
+		std::unordered_map<std::string, bool> used;
+		for (const auto& i : sbuffers) {
+			const auto& sbuffer = i.second;
+			if (
+				sbuffer.stage & (1 << stage) &&
+				used.find(sbuffer.strct) == used.end()
+			) {
+				const Struct& s = structs[sbuffer.strct];
+				ss << "struct " << s.name << "{\n";
+				for (auto& v : s.vars)
+					ss << "\t" << v.tname << " " << v.name << ";\n";
+				ss << "};\n";
+				used[sbuffer.strct] = true;
+			}
+		}
+	}
+
+	void add_sbuffers(std::stringstream& ss, Shader_Type stage) {
+		add_sbuffer_structs(ss, stage);
+		for (const auto& i : sbuffers) {
+			const auto& sbuffer = i.second;
+			if (sbuffer.stage & (1 << stage)) {
+				Descriptor* d = find_desc(i.first.c_str());
+				assert(d != 0);
+				ss << "layout (std140, binding = " << d->slot << ") ";
+				ss << "readonly buffer _SBuffer" << d->slot << " {\n";
+				ss << "\t" << sbuffer.strct << " ";
+				ss << i.first << "[];\n";
+				ss << "};\n";
+			}
+		}
+	}
+
 	std::string build_vs() {
 		std::stringstream ss;
 		size_t i, li = bindings.size();
@@ -490,6 +573,7 @@ struct Desc {
 		}
 		add_textures(ss, shader_type_vertex);
 		add_cbuffers(ss, shader_type_vertex);
+		add_sbuffers(ss, shader_type_vertex);
 		return ss.str();
 	}
 
@@ -510,6 +594,7 @@ struct Desc {
 		}
 		add_textures(ss, shader_type_fragment);
 		add_cbuffers(ss, shader_type_fragment);
+		add_sbuffers(ss, shader_type_fragment);
 		return ss.str();
 	}
 };
-- 
cgit v1.2.3-54-g00ecf