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Updated integer intrinsics documentation

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[ROCm/hip commit: 2c01480131]
Этот коммит содержится в:
Maneesh Gupta
2016-02-12 13:58:35 +05:30
родитель fcd154097f
Коммит 99052abbdb
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projects/hip/docs/markdown/hip_kernel_language.md
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@@ -363,27 +363,27 @@ Following is the list of supported double precision mathematical functions.
<sub><b id="f2"><sup>[1]</sup></b> __RETURN_TYPE is dependent on compiler. It is usually 'int' for C compilers and 'bool' for C++ compilers.</sub> [↩](#a2) <sub><b id="f2"><sup>[1]</sup></b> __RETURN_TYPE is dependent on compiler. It is usually 'int' for C compilers and 'bool' for C++ compilers.</sub> [↩](#a2)
### Integer Intrinsics ### Integer Intrinsics
Following is the list of supported integer intrinsics. Following is the list of supported integer intrinsics. Note that intrinsics are supported on device only.
| **Function** | **Supported on Host** | **Supported on Device** | | **Function** |
| --- | --- | --- | | --- |
| unsigned int __brev ( unsigned int x ) <br><sub>Reverse the bit order of a 32 bit unsigned integer.</sub> | ✓ | ✓ | | unsigned int __brev ( unsigned int x ) <br><sub>Reverse the bit order of a 32 bit unsigned integer.</sub> |
| unsigned long long int __brevll ( unsigned long long int x ) <br><sub>Reverse the bit order of a 64 bit unsigned integer. </sub> | ✓ | ✓ | | unsigned long long int __brevll ( unsigned long long int x ) <br><sub>Reverse the bit order of a 64 bit unsigned integer. </sub> |
| int __clz ( int x ) <br><sub>Return the number of consecutive high-order zero bits in a 32 bit integer.</sub> | ✓ | ✓ | | int __clz ( int x ) <br><sub>Return the number of consecutive high-order zero bits in a 32 bit integer.</sub> |
| unsigned int __clz(unsigned int x) <br><sub>Return the number of consecutive high-order zero bits in 32 bit unsigned integer.</sub> | ✓ | ✗ | | unsigned int __clz(unsigned int x) <br><sub>Return the number of consecutive high-order zero bits in 32 bit unsigned integer.</sub> |
| int __clzll ( long long int x ) <br><sub>Count the number of consecutive high-order zero bits in a 64 bit integer.</sub> | ✓ | ✓ | | int __clzll ( long long int x ) <br><sub>Count the number of consecutive high-order zero bits in a 64 bit integer.</sub> |
| unsigned int __clzll(long long int x) <br><sub>Return the number of consecutive high-order zero bits in 64 bit signed integer.</sub> | ✓ | ✗ | | unsigned int __clzll(long long int x) <br><sub>Return the number of consecutive high-order zero bits in 64 bit signed integer.</sub> |
| unsigned int __ffs(unsigned int x) <br><sub>Find the position of least signigicant bit set to 1 in a 32 bit unsigned integer.<sup id="a3">[1](#f3)</sup></sub> | ✓ | ✓| | unsigned int __ffs(unsigned int x) <br><sub>Find the position of least signigicant bit set to 1 in a 32 bit unsigned integer.<sup id="a3">[1](#f3)</sup></sub> |
| unsigned int __ffs(int x) <br><sub>Find the position of least signigicant bit set to 1 in a 32 bit signed integer.</sub> | ✗ | ✓ | | unsigned int __ffs(int x) <br><sub>Find the position of least signigicant bit set to 1 in a 32 bit signed integer.</sub> |
| unsigned int __ffsll(unsigned long long int x) <br><sub>Find the position of least signigicant bit set to 1 in a 64 bit unsigned integer.<sup>[1](#f3)</sup></sub> | ✓ | ✓ | | unsigned int __ffsll(unsigned long long int x) <br><sub>Find the position of least signigicant bit set to 1 in a 64 bit unsigned integer.<sup>[1](#f3)</sup></sub> |
| unsigned int __ffsll(long long int x) <br><sub>Find the position of least signigicant bit set to 1 in a 64 bit signed integer.</sub> | ✗ | ✓ | | unsigned int __ffsll(long long int x) <br><sub>Find the position of least signigicant bit set to 1 in a 64 bit signed integer.</sub> |
| unsigned int __popc ( unsigned int x ) <br><sub>Count the number of bits that are set to 1 in a 32 bit integer.</sub> | ✓ | ✓ | | unsigned int __popc ( unsigned int x ) <br><sub>Count the number of bits that are set to 1 in a 32 bit integer.</sub> |
| int __popcll ( unsigned long long int x )<br><sub>Count the number of bits that are set to 1 in a 64 bit integer.</sub> | ✓ | ✓ | | int __popcll ( unsigned long long int x )<br><sub>Count the number of bits that are set to 1 in a 64 bit integer.</sub> |
<sub><b id="f3"><sup>[1]</sup></b> <sub><b id="f3"><sup>[1]</sup></b>
The hcc implementation of __ffs() and __ffsll() contains code to add a constant +1 to produce the ffs result format. The hcc implementation of __ffs() and __ffsll() contains code to add a constant +1 to produce the ffs result format.
For the cases where this overhead is not acceptable and programmer is willing to specialize for the platform, For the cases where this overhead is not acceptable and programmer is willing to specialize for the platform,
hcc provides hc::__lastbit_u32_u32(unsigned int input) and hc::__lastbit_u32_u64(unsigned long long int input). hcc provides hc::__lastbit_u32_u32(unsigned int input) and hc::__lastbit_u32_u64(unsigned long long int input).
The index returned by __lastbit_ instructions starts at 0, while for ffs the index starts at 1. The index returned by __lastbit_ instructions starts at -1, while for ffs the index starts at 0.
## Texture Functions ## Texture Functions