Implementation:Alibaba MNN RapidJSON Stdint

Knowledge Sources	Alibaba_MNN RapidJSON
Domains	JSON_Parsing, Compatibility
Last Updated	2026-02-10 12:00 GMT

Overview

3rd_party/rapidjson/msinttypes/stdint.h (300 lines) provides an ISO C99-compliant <stdint.h> implementation for older Microsoft Visual C++ compilers. This vendored header ensures that fixed-width integer types (int8_t, uint32_t, int64_t, etc.) are available when building RapidJSON (and Alibaba MNN) on Windows platforms with MSVC versions prior to Visual Studio 2010.

Usage note: Vendored dependency used internally by MNN for JSON configuration parsing (model configs, LLM configs). Not directly imported by end users.

Conditional Compilation

The header is MSVC-only and uses version detection to determine which definitions are needed:

#ifndef _MSC_VER
#error "Use this header only with Microsoft Visual C++ compilers!"
#endif

// MSVC 2010+ has its own stdint.h, but INT64_C() generates warnings
#if _MSC_VER >= 1600
#include <stdint.h>
// Redefine constant macros to suppress warnings
#undef INT8_C
#undef INT16_C
#undef INT32_C
#undef INT64_C
// ... redefinitions ...
#else
// Full type definitions for older MSVC
#endif

Defined Types

Exact-Width Integer Types

Type	Width	MSVC Mapping
`int8_t`	8-bit signed	`signed __int8`
`uint8_t`	8-bit unsigned	`unsigned __int8`
`int16_t`	16-bit signed	`signed __int16`
`uint16_t`	16-bit unsigned	`unsigned __int16`
`int32_t`	32-bit signed	`signed __int32`
`uint32_t`	32-bit unsigned	`unsigned __int32`
`int64_t`	64-bit signed	`signed __int64`
`uint64_t`	64-bit unsigned	`unsigned __int64`

Minimum-Width Types

Types like int_least8_t, int_least16_t, int_least32_t, int_least64_t and their unsigned counterparts.

Fastest Minimum-Width Types

Types like int_fast8_t, int_fast16_t, etc., mapped to the fastest available integer type of at least that width.

Maximum-Width and Pointer Types

intmax_t / uintmax_t -- mapped to 64-bit integers
intptr_t / uintptr_t -- pointer-width integers (32 or 64 bit depending on platform)

Limit and Constant Macros

The header defines limit macros (e.g., INT8_MIN, INT8_MAX, UINT8_MAX, INT64_MIN, INT64_MAX) and integer constant macros (e.g., INT8_C(val), UINT64_C(val)) following the C99 specification. These are conditionally defined based on __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS.

MSVC Version Notes

MSVC < 1600 (VS 2010) -- All types and macros are fully defined by this header
MSVC >= 1600 -- Defers to the native <stdint.h> but overrides the INT64_C/UINT64_C macros to suppress compiler warning C4307

License

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