gdiplus: Improve performance of units_to_pixels by not using division.

Single float division (divss) is at least four time slower, than multiplication (mulss). More information: https://www.agner.org/optimize/instruction_tables.pdf The units_to_pixels was optimized to use only multiplication (mulss), and avoid using divisions (divss).

gdiplus: Improve performance of units_to_pixels by not using division.
012f6106 · Bartosz Kosiorek · Alexandre Julliard · 059094c1 · 012f6106
Commit 012f6106 authored Oct 24, 2023 by Bartosz Kosiorek Committed by Alexandre Julliard Oct 25, 2023
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gdiplus.c dlls/gdiplus/gdiplus.c +6 -4

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--- a/dlls/gdiplus/gdiplus.c
+++ b/dlls/gdiplus/gdiplus.c
@@ -36,7 +36,9 @@
 WINE_DEFAULT_DEBUG_CHANNEL(gdiplus);

 static const REAL mm_per_inch = 25.4;
+static const REAL inch_per_mm = 1.0 / 25.4;
 static const REAL point_per_inch = 72.0;
+static const REAL inch_per_point = 1.0 / 72.0;

 static Status WINAPI NotificationHook(ULONG_PTR *token)
 {
@@ -333,17 +335,17 @@ REAL units_to_pixels(REAL units, GpUnit unit, REAL dpi, BOOL printer_display)
        return units;
    case UnitDisplay:
        if (printer_display)
-            return units * dpi / 100.0;
+            return units * dpi * 0.01f;
        else
            return units;
    case UnitPoint:
-        return units * dpi / point_per_inch;
+        return units * dpi * inch_per_point;
    case UnitInch:
        return units * dpi;
    case UnitDocument:
-        return units * dpi / 300.0; /* Per MSDN */
+        return units * dpi * (1.0f / 300.0f); /* Per MSDN */
    case UnitMillimeter:
-        return units * dpi / mm_per_inch;
+        return units * dpi * inch_per_mm;
    default:
        FIXME("Unhandled unit type: %d\n", unit);
        return 0;