video_core: Rework clear values (#1381)

* Clear color convertion

* Add missing formats

* Add swap handling

* Format bits and offsets

* clang-format

* Make num_components const

* Initialize alpha to 1

* Handle SnormNz as Snorm

* Don0t leave accidental nonzero values

* parallel3 for linux-qt

* Move number_utils to common

src/common/number_utils.cpp

@@ -0,0 +1,161 @@
+// SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <array>
+#include <half.hpp>
+
+#include "common/number_utils.h"
+#include "video_core/amdgpu/pixel_format.h"
+#include "video_core/amdgpu/types.h"
+
+#define UF11_EXPONENT_SHIFT 6
+#define UF10_EXPONENT_SHIFT 5
+
+#define RGB9E5_MANTISSA_BITS 9
+#define RGB9E5_EXP_BIAS 1
+
+#define F32_INFINITY 0x7f800000
+
+namespace NumberUtils {
+
+float Uf11ToF32(u16 val) {
+    union {
+        float f;
+        u32 ui;
+    } f32;
+
+    int exponent = (val & 0x07c0) >> UF11_EXPONENT_SHIFT;
+    int mantissa = (val & 0x003f);
+
+    f32.f = 0.0;
+
+    if (exponent == 0) {
+        if (mantissa != 0) {
+            const float scale = 1.0 / (1 << 20);
+            f32.f = scale * mantissa;
+        }
+    } else if (exponent == 31) {
+        f32.ui = F32_INFINITY | mantissa;
+    } else {
+        float scale, decimal;
+        exponent -= 15;
+        if (exponent < 0) {
+            scale = 1.0f / (1 << -exponent);
+        } else {
+            scale = (float)(1 << exponent);
+        }
+        decimal = 1.0f + (float)mantissa / 64;
+        f32.f = scale * decimal;
+    }
+
+    return f32.f;
+}
+
+float Uf10ToF32(u16 val) {
+    union {
+        float f;
+        u32 ui;
+    } f32;
+
+    int exponent = (val & 0x03e0) >> UF10_EXPONENT_SHIFT;
+    int mantissa = (val & 0x001f);
+
+    f32.f = 0.0;
+
+    if (exponent == 0) {
+        if (mantissa != 0) {
+            const float scale = 1.0 / (1 << 19);
+            f32.f = scale * mantissa;
+        }
+    } else if (exponent == 31) {
+        f32.ui = F32_INFINITY | mantissa;
+    } else {
+        float scale, decimal;
+        exponent -= 15;
+        if (exponent < 0) {
+            scale = 1.0f / (1 << -exponent);
+        } else {
+            scale = (float)(1 << exponent);
+        }
+        decimal = 1.0f + (float)mantissa / 32;
+        f32.f = scale * decimal;
+    }
+
+    return f32.f;
+}
+
+float Uf16ToF32(u16 val) {
+    return half_float::half_cast<float>(reinterpret_cast<half_float::half&>(val));
+}
+
+float U2ToUnorm(u8 val) {
+    static constexpr auto c = 1.0f / 3.0f;
+    return float(val * c);
+}
+
+float S2ToSnorm(s8 val) {
+    static constexpr auto c = 1.0f / 1.0f;
+    return float(val * c);
+}
+
+float U4ToUnorm(u8 val) {
+    static constexpr auto c = 1.0f / 15.0f;
+    return float(val * c);
+}
+
+float S4ToSnorm(s8 val) {
+    static constexpr auto c = 1.0f / 7.0f;
+    return float(val * c);
+}
+
+float U5ToUnorm(u8 val) {
+    static constexpr auto c = 1.0f / 31.0f;
+    return float(val * c);
+}
+
+float S5ToSnorm(s8 val) {
+    static constexpr auto c = 1.0f / 15.0f;
+    return float(val * c);
+}
+
+float U6ToUnorm(u8 val) {
+    static constexpr auto c = 1.0f / 63.0f;
+    return float(val * c);
+}
+
+float S6ToSnorm(s8 val) {
+    static constexpr auto c = 1.0f / 31.0f;
+    return float(val * c);
+}
+
+float U8ToUnorm(u8 val) {
+    static constexpr auto c = 1.0f / 255.0f;
+    return float(val * c);
+}
+
+float S8ToSnorm(s8 val) {
+    static constexpr auto c = 1.0f / 127.0f;
+    return float(val * c);
+}
+
+float U10ToUnorm(u16 val) {
+    static constexpr auto c = 1.0f / 1023.0f;
+    return float(val * c);
+}
+
+float S10ToSnorm(s16 val) {
+    static constexpr auto c = 1.0f / 511.0f;
+    return float(val * c);
+}
+
+float U16ToUnorm(u16 val) {
+    static constexpr auto c = 1.0f / 65535.0f;
+    return float(val * c);
+}
+
+float S16ToSnorm(s16 val) {
+    static constexpr auto c = 1.0f / 32767.0f;
+    return float(val * c);
+}
+
+} // namespace NumberUtils