We describe various issues caused by the lack of round-to-nearest mode in the \textit{gcc} compiler implementation of the fixed-point arithmetic data types and operations. We demonstrate that round-to-nearest is not performed in the conversion of constants, conversion from one numerical type to a less precise type and results of multiplications. Furthermore, we show that mixed-precision operations in fixed-point arithmetic lose precision on arguments, even before carrying out arithmetic operations. The ISO 18037:2008 standard was created to standardize C language extensions, including fixed-point arithmetic, for embedded systems. Embedded systems are usually based on ARM processors, of which approximately 100 billion have been manufactured by now. Therefore, the observations about numerical issues that we discuss in this paper can be rather dangerous and are important to address, given the wide ranging type of applications that these embedded systems are running.

中文翻译：

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ISO 18037:2008 标准定点算法的 GCC 实现中的舍入问题

我们描述了在定点算术数据类型和运算的 \textit{gcc} 编译器实现中缺乏舍入到最近模式导致的各种问题。我们证明了舍入到最近的转换不是在常量的转换、从一种数值类型到不太精确的类型的转换以及乘法结果中执行的。此外，我们表明，即使在执行算术运算之前，定点算术中的混合精度运算也会失去参数的精度。ISO 18037:2008 标准旨在标准化嵌入式系统的 C 语言扩展，包括定点算法。嵌入式系统通常基于 ARM 处理器，目前已经制造了大约 1000 亿个。所以，