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Invalid answer when casting from float to int

John Griswold

The following code, simple as it is, fails to work. I suspect it's a brain short
on my part, and willingly accept the public humiliation. Perhaps it's an actual
problem that I am just now uncovering. I am new to the toolset, so all bets are off.
The tool is a bit on the dated side. Perhaps there is an update that I'm missing.

TIA for any help.

John

IDE-Version:
µVision V4.72.10.0
Copyright (C) 2013 ARM Ltd and ARM Germany GmbH. All rights reserved.

Tool Version Numbers:
Toolchain: MDK-ARM Standard Cortex-M only Version: 4.72.1.0
Toolchain Path: C:\Keil\ARM\ARMCC\bin\
C Compiler: Armcc.Exe V5.03.0.76
Assembler: Armasm.Exe V5.03.0.76
Linker/Locator: ArmLink.Exe V5.03.0.76
Librarian: ArmAr.Exe V5.03.0.76
Hex Converter: FromElf.Exe V5.03.0.76
CPU DLL: SARMCM3.DLL V4.72.1.0
Dialog DLL: DARMP1.DLL V1.22.0.11
Target DLL: UL2CM3.DLL V1.150.11.0
Dialog DLL: TARMP1.DLL V1.22.0.11

        float           gain;
        float           fTemp;
        uint32_t        lTemp;
        uint16_t        temp;

        //      On entry, gain is 27.893
        fTemp = gain * 1000.0;        //  gain - preserve three decimal places
        //      fTemp now 27893.0
        lTemp = (uint32_t)fTemp;
        //      lTemp now 0x6C5F (27743, while I expect 27893)
        temp = lTemp & 0xFFFF;
        //      temp now 27743
        //      WTH?

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