PCMPESTRI - Packed CoMPare Explicit STRing Index
PCMPESTRM - Packed CoMPare Explicit STRing Mask
PCMPISTRI - Packed CoMPare Implicit STRing Index
PCMPISTRM - Packed CoMPare Implicit STRing Mask

PCMPESTRI xmm1, xmm2/m128, imm8    (S4.2
VPCMPESTRI xmm1, xmm2/m128, imm8    (V1
int _mm_cmpestri (__m128i a, int la, __m128i b, int lb, const int imm8);
int _mm_cmpestr? (__m128i a, int la, __m128i b, int lb, const int imm8);

PCMPESTRM xmm1, xmm2/m128, imm8    (S4.2
VPCMPESTRM xmm1, xmm2/m128, imm8    (V1
__m128i _mm_cmpestrm (__m128i a, int la, __m128i b, int lb, const int imm8);
int _mm_cmpestr? (__m128i a, int la, __m128i b, int lb, const int imm8);
PCMPISTRI xmm1, xmm2/m128, imm8    (S4.2
VPCMPISTRI xmm1, xmm2/m128, imm8    (v1
int _mm_cmpistri (__m128i a, __m128i b, const int imm8);
int _mm_cmpistr? (__m128i a, __m128i b, const int imm8);
PCMPISTRM xmm1, xmm2/m128, imm8    (S4.2
VPCMPISTRM xmm1, xmm2/m128, imm8    (V1
__m128i _mm_cmpistrm (__m128i a, __m128i b, const int imm8);
int _mm_cmpistr? (__m128i a, __m128i b, const int imm8);

Basics

Instruction / intrinsic names don't specify what to do, but how the input/output data are passed.

ESTR* Explicit length: specify the number of BYTES / WORDS of the input string.
ISTR* Implicit length: indicate the end of the input string with the terminating NUL.

*STRI returns index
*STRM returns mask
*str? ?=a/c/o/s/z returns the velue of flags

What to do is specified in imm8 bit 3:2.

imm8 bit3:2 mode what to do
00 Equal Any Test if any of the specified characters are in the input string.
01 Ranges Test if any characters within the specified ranges are in the input string.
10 Equal Each Test if the input strings are equal.
11 Equal Ordered Test if the needle string is in the haystack string.

Character format is specified in imm8 bit 1:0.

imm8 bit1:0 character format
00 unsigned BYTE
01 unsigned WORD
10 signed BYTE
11 signed WORD

The lowest BYTE/WORD is the start of the input string. Lower BYTEs/WORDs up to the end of the string are VALID. Upper BYTEs/WORDs beyond the end of the string are INVALID (if any).

For ESTR* instruction, the number of BYTEs/WORDs is the absolute value of the value specified. If the abosolute value > 16 (BYTEs) or 8 (WORDs), 16 or 8 is used.

For ISTR* instruction, NUL character itself is INVALID data. If there is no NUL, 16 BYTEs / 8 WORDs are all VALID.

Set each bit of IntRes1 by the mode specified

Mode 00: Equal Any - Test if any of the specified characters are in the input string

Mode 01: Ranges - Test if any characters within the specified ranges are in the input string

Mode 10: Equal Each - Test if the input strings are equal

Mode 11: Equal Ordered - Test if the needle string is in the haystack string

Convert IntRes1 to IntRes2

Each bit of IntRes1 is converted to each bit of IntRes2 by the method specified in imm8 bit 5:4.

imm8 bit5:4 name process
00 Positive Polarity(+) Copy IntRes1 to IntRes2.
01 Negative Polarity(-) Invert each bit of IntRes1 and set to IntRes2.
10 Masked(+) Copy IntRes1 to IntRes2.
11 Masked(-) If the corresponding BYTE / WORD of (2) xmm2/m128 b is valid
invert the bit of IntRes1 and set to IntRes2.
else copy the bit of IntRes1 to IntRes2.

Determine the return value from IntRes2

*STRI instruction returns the index 0 to 15 or 7 in ECX/RCX register (int type return value). If no bit is set, 16 or 8 is returned.

imm8 bit 6 return value
0 The bit index number of the least significant set bit of IntRes2.
1 The bit index number of the most significant set bit of IntRes2.

*STRM instruction returns IntRes2 in XMM0 register (__m128i type return value).

imm8 bit 6 return value
0 Returns IntRes2 in the lowest 16 / 8 bits.
1 Returns 128-bit data that each bit of IntRes2 is expanded to BYTE / WORD.

Flags

CF 0: IntRes2 == 0
1: IntRes2 != 0
ZF 0: All elements of (2) xmm2/m128 b are valid.
1: Not all elements of (2) xmm2/m128 b are valid.
SF 0: All elements of (1) xmm1 a are valid.
1: Not all elements of (1) xmm1 a are valid.
OF The least significant bit of IntRes2.
AF 0
PF 0

*str? intrinsic returns the value of one bit of the flags (0 or 1).

*strc CF
*strz ZF
*strs SF
*stro OF
*stra if (CF == 0 && ZF == 0), returns 1
else returns 0.

imm8 summary

bit   value meaning
1:0 Character Format 00 unsigned BYTE
01 unsigned WORD
10 signed BYTE
11 signed WORD
3:2 Mode 00 Equal Any Test if any of the specified characters are in the input string
01 Ranges Test if any characters within the specified ranges are in the input string
10 Equal Each Test if the input strings are equal
11 Equal Ordered Test if the needle string is in the haystack string
5:4 Polarity 00 Positive Polarity(+) Copy IntRes1 to IntRes2.
01 Negative Polarity(-) Invert each bit of IntRes1 and set to IntRes2.
10 Masked(+) Copy IntRes1 to IntRes2.
11 Masked(-) If the corresponding BYTE / WORD of (2) xmm2/m128 b is valid
invert the bit of IntRes1 and set to IntRes2.
else copy the bit of IntRes1 to IntRes2.
6 Return Value 0 *STRI instruction: returns the bit index number of the least significant set bit of IntRes2.
*STRM instruction: returns IntRes2 bits in the lowest bits.
1 *STRI instruction: returns the bit index number of the most significant set bit of IntRes2.
*STRM instruction: returns 128-bit data that each bit of IntRes2 is expanded to BYTE / WORD.
7 unused must be 0.

Implicit Registers

register instruction
EAX/RAX ESTR* (IN) the number of BYTEs/WORDs of operand 1
EDX/RDX ESTR* (IN) the number of BYTEs/WORDs of operand 2
ECX/RCX *STRI (OUT) the index number
XMM0 *STRM (OUT) mask

 


x86/x64 SIMD Instruction List  Feedback