call c code from python

redoktober · Post by **redoktober** » Wed Feb 10, 2010 10:45 pm

hey!

suppose i have the following python script:

import platform

print platform.architecture()
print platform.python_version()
print platform.uname()

then, i have the following collection of C code, which uses the CPUID instruction through inline assembly.

first comes cpuid.h:

Code: Select all

//cpuid.h

#ifndef _INC_CPUID
#define _INC_CPUID

#define _CPU_FEATURE_MMX    0x0001
#define _CPU_FEATURE_SSE    0x0002
#define _CPU_FEATURE_SSE2   0x0004
#define _CPU_FEATURE_3DNOW  0x0008

#define _MAX_VNAME_LEN  13
#define _MAX_MNAME_LEN  30

typedef struct _processor_info {
    char v_name[_MAX_VNAME_LEN];        // vendor name
    char model_name[_MAX_MNAME_LEN];    // name of model
                                        // e.g. Intel Pentium-Pro
    int family;                         // family of the processor
                                        // e.g. 6 = Pentium-Pro architecture
    int model;                          // model of processor
                                        // e.g. 1 = Pentium-Pro for family = 6
    int stepping;                       // processor revision number
    int feature;                        // processor feature
                                        // (same as return value from _cpuid)
    int os_support;                     // does OS Support the feature?
    int checks;                         // mask of checked bits in feature
                                        // and os_support fields
} _p_info;

#ifdef __cplusplus
extern "C"
#endif
int _cpuid (_p_info *);

#endif

then, we have cpuid.c:

Code: Select all

#include <windows.h>
#include "cpuid.h"


// These are the bit flags that get set on calling cpuid
// with register eax set to 1
#define _MMX_FEATURE_BIT        0x00800000
#define _SSE_FEATURE_BIT        0x02000000
#define _SSE2_FEATURE_BIT       0x04000000

// This bit is set when cpuid is called with
// register set to 80000001h (only applicable to AMD)
#define _3DNOW_FEATURE_BIT      0x80000000

// These are the names of the various processors
#define PROC_AMD_AM486          "AMD Am486"
#define PROC_AMD_K5             "AMD K5"
#define PROC_AMD_K6             "AMD K6"
#define PROC_AMD_K6_2           "AMD K6-2"
#define PROC_AMD_K6_3           "AMD K6-3"
#define PROC_AMD_ATHLON         "AMD Athlon"
#define PROC_INTEL_486DX        "INTEL 486DX"
#define PROC_INTEL_486SX        "INTEL 486SX"
#define PROC_INTEL_486DX2       "INTEL 486DX2"
#define PROC_INTEL_486SL        "INTEL 486SL"
#define PROC_INTEL_486SX2       "INTEL 486SX2"
#define PROC_INTEL_486DX2E      "INTEL 486DX2E"
#define PROC_INTEL_486DX4       "INTEL 486DX4"
#define PROC_INTEL_PENTIUM      "INTEL Pentium"
#define PROC_INTEL_PENTIUM_MMX  "INTEL Pentium-MMX"
#define PROC_INTEL_PENTIUM_PRO  "INTEL Pentium-Pro"
#define PROC_INTEL_PENTIUM_II   "INTEL Pentium-II"
#define PROC_INTEL_CELERON      "INTEL Celeron"
#define PROC_INTEL_PENTIUM_III  "INTEL Pentium-III"
#define PROC_INTEL_PENTIUM_4    "INTEL Pentium-4"
#define PROC_CYRIX              "Cyrix"
#define PROC_CENTAUR            "Centaur"
#define PROC_UNKNOWN            "Unknown"

// This is the maximum length of the vendor name
#define MAX_VNAME_LENGTH        12
	
int IsCPUID()
{
    __try {
        _asm {
            xor eax, eax
            cpuid
        }
    }
	#pragma warning (suppress: 6320)
    __except (EXCEPTION_EXECUTE_HANDLER) {
        return 0;
    }
    return 1;
}


/***
* int _os_support(int feature)
*   - Checks if OS Supports the capablity or not
*
* Entry:
*   feature: the feature we want to check if OS supports it.
*
* Exit:
*   Returns 1 if OS support exist and 0 when OS doesn't support it.
*
****************************************************************/

int _os_support(int feature)
{
    __try {
        switch (feature) {
        case _CPU_FEATURE_SSE:
            __asm {
                xorps xmm0, xmm0        // executing SSE instruction
            }
            break;
        case _CPU_FEATURE_SSE2:
            __asm {
                xorpd xmm0, xmm0        // executing SSE2 instruction
            }
            break;
        case _CPU_FEATURE_3DNOW:
            __asm {
                pfrcp mm0, mm0          // executing 3DNow! instruction
                emms
            }
            break;
        case _CPU_FEATURE_MMX:
            __asm {
                pxor mm0, mm0           // executing MMX instruction
                emms
            }
            break;
        }
    }
	#pragma warning (suppress: 6320)
    __except (EXCEPTION_EXECUTE_HANDLER) {
        if (_exception_code() == STATUS_ILLEGAL_INSTRUCTION) {
            return 0;
        }
        return 0;
    }
    return 1;
}


/***
*
* void map_mname(int, int, const char *, char *)
*   - Maps family and model to processor name
*
****************************************************/


void map_mname(int family, int model, const char *v_name, char *m_name)
{
    // Default to name not known
    m_name[0] = '\0';

    if (!strncmp("AuthenticAMD", v_name, 12)) {
        switch (family) { // extract family code
        case 4: // Am486/AM5x86
            strcpy_s (m_name, sizeof(PROC_AMD_AM486), PROC_AMD_AM486);
            break;

        case 5: // K6
            switch (model) { // extract model code
            case 0:
            case 1:
            case 2:
            case 3:
                strcpy_s (m_name, sizeof(PROC_AMD_K5), PROC_AMD_K5);
                break;
            case 6:
            case 7:
                strcpy_s (m_name, sizeof(PROC_AMD_K6), PROC_AMD_K6);
                break;
            case 8:
                strcpy_s (m_name, sizeof(PROC_AMD_K6_2), PROC_AMD_K6_2);
                break;
            case 9:
            case 10:
            case 11:
            case 12:
            case 13:
            case 14:
            case 15:
                strcpy_s (m_name, sizeof(PROC_AMD_K6_3), PROC_AMD_K6_3);
                break;
            }
            break;

        case 6: // Athlon
            // No model numbers are currently defined
            strcpy_s (m_name, sizeof(PROC_AMD_ATHLON), PROC_AMD_ATHLON);
            break;
        }
    }
    else if (!strncmp("GenuineIntel", v_name, 12)) {
        switch (family) { // extract family code
        case 4:
            switch (model) { // extract model code
            case 0:
            case 1:
                strcpy_s (m_name, sizeof(PROC_INTEL_486DX), PROC_INTEL_486DX);
                break;
            case 2:
                strcpy_s (m_name, sizeof(PROC_INTEL_486SX), PROC_INTEL_486SX);
                break;
            case 3:
                strcpy_s (m_name, sizeof(PROC_INTEL_486DX2), PROC_INTEL_486DX2);
                break;
            case 4:
                strcpy_s (m_name, sizeof(PROC_INTEL_486SL), PROC_INTEL_486SL);
                break;
            case 5:
                strcpy_s (m_name, sizeof(PROC_INTEL_486SX2), PROC_INTEL_486SX2);
                break;
            case 7:
                strcpy_s (m_name, sizeof(PROC_INTEL_486DX2E), PROC_INTEL_486DX2E);
                break;
            case 8:
                strcpy_s (m_name, sizeof(PROC_INTEL_486DX4), PROC_INTEL_486DX4);
                break;
            }
            break;

        case 5:
            switch (model) { // extract model code
            case 1:
            case 2:
            case 3:
                strcpy_s (m_name, sizeof(PROC_INTEL_PENTIUM), PROC_INTEL_PENTIUM);
                break;
            case 4:
                strcpy_s (m_name, sizeof(PROC_INTEL_PENTIUM_MMX), PROC_INTEL_PENTIUM_MMX);
                break;
            }
            break;

        case 6:
            switch (model) { // extract model code
            case 1:
                strcpy_s (m_name, sizeof(PROC_INTEL_PENTIUM_PRO), PROC_INTEL_PENTIUM_PRO);
                break;
            case 3:
            case 5:
                strcpy_s (m_name, sizeof(PROC_INTEL_PENTIUM_II), PROC_INTEL_PENTIUM_II);
                break;  // actual differentiation depends on cache settings
            case 6:
                strcpy_s (m_name, sizeof(PROC_INTEL_CELERON), PROC_INTEL_CELERON);
                break;
            case 7:
            case 8:
            case 10:
                strcpy_s (m_name, sizeof(PROC_INTEL_PENTIUM_III), PROC_INTEL_PENTIUM_III);
                break;  // actual differentiation depends on cache settings
            }
            break;

        case 15 | (0x00 << 4): // family 15, extended family 0x00
            switch (model) {
            case 0:
                strcpy_s (m_name, sizeof(PROC_INTEL_PENTIUM_4), PROC_INTEL_PENTIUM_4);
                break;
            }
            break;
        }
    }
    else if (!strncmp("CyrixInstead", v_name, 12)) {
        strcpy_s (m_name, sizeof(PROC_CYRIX), PROC_CYRIX);
    }
    else if (!strncmp("CentaurHauls", v_name, 12)) {
        strcpy_s (m_name, sizeof(PROC_CENTAUR), PROC_CENTAUR);
    }

    if (!m_name[0]) {
        strcpy_s (m_name, sizeof(PROC_UNKNOWN), PROC_UNKNOWN);
    }
}


/***
*
* int _cpuid (_p_info *pinfo)
*
* Entry:
*
*   pinfo: pointer to _p_info.
*
* Exit:
*
*   Returns int with capablity bit set even if pinfo = NULL
*
****************************************************/


int _cpuid (_p_info *pinfo)
{
    DWORD dwStandard = 0;
    DWORD dwFeature = 0;
    DWORD dwMax = 0;
    DWORD dwExt = 0;
    int feature = 0;
    int os_support = 0;
    union {
		char cBuf[MAX_VNAME_LENGTH + 1]; // add one for the null terminator
        struct {
            DWORD dw0;
            DWORD dw1;
            DWORD dw2;
        } s;
    } Ident;

    if (!IsCPUID()) {
        return 0;
    }

    _asm {
        push ebx
        push ecx
        push edx

        // get the vendor string
        xor eax, eax
        cpuid
        mov dwMax, eax
        mov Ident.s.dw0, ebx
        mov Ident.s.dw1, edx
        mov Ident.s.dw2, ecx

        // get the Standard bits
        mov eax, 1
        cpuid
        mov dwStandard, eax
        mov dwFeature, edx

        // get AMD-specials
        mov eax, 80000000h
        cpuid
        cmp eax, 80000000h
        jc notamd
        mov eax, 80000001h
        cpuid
        mov dwExt, edx

notamd:
        pop ecx
        pop ebx
        pop edx
    }

    if (dwFeature & _MMX_FEATURE_BIT) {
        feature |= _CPU_FEATURE_MMX;
        if (_os_support(_CPU_FEATURE_MMX))
            os_support |= _CPU_FEATURE_MMX;
    }
    if (dwExt & _3DNOW_FEATURE_BIT) {
        feature |= _CPU_FEATURE_3DNOW;
        if (_os_support(_CPU_FEATURE_3DNOW))
            os_support |= _CPU_FEATURE_3DNOW;
    }
    if (dwFeature & _SSE_FEATURE_BIT) {
        feature |= _CPU_FEATURE_SSE;
        if (_os_support(_CPU_FEATURE_SSE))
            os_support |= _CPU_FEATURE_SSE;
    }
    if (dwFeature & _SSE2_FEATURE_BIT) {
        feature |= _CPU_FEATURE_SSE2;
        if (_os_support(_CPU_FEATURE_SSE2))
            os_support |= _CPU_FEATURE_SSE2;
    }

    if (pinfo) {
        memset(pinfo, 0, sizeof(_p_info));

        pinfo->os_support = os_support;
        pinfo->feature = feature;
        pinfo->family = (dwStandard >> 8) & 0xF; // retrieve family
        if (pinfo->family == 15) {               // retrieve extended family
            pinfo->family |= (dwStandard >> 16) & 0xFF0;
        }
        pinfo->model = (dwStandard >> 4) & 0xF;  // retrieve model
        if (pinfo->model == 15) {                // retrieve extended model
            pinfo->model |= (dwStandard >> 12) & 0xF;
        }
        pinfo->stepping = (dwStandard) & 0xF;    // retrieve stepping

        Ident.cBuf[MAX_VNAME_LENGTH] = 0;
        strcpy_s(pinfo->v_name, MAX_VNAME_LENGTH + 1, Ident.cBuf);

        map_mname(pinfo->family, 
                  pinfo->model,
                  pinfo->v_name,
                  pinfo->model_name);

        pinfo->checks = _CPU_FEATURE_MMX |
                        _CPU_FEATURE_SSE |
                        _CPU_FEATURE_SSE2 |
                        _CPU_FEATURE_3DNOW;
    }

    return feature;
}

finally, test.cpp, a small C++ snippet which tests the whole lot:

Code: Select all

#include <stdio.h>
#include "cpuid.h"

void expand(int avail, int mask)
{
    if (mask & _CPU_FEATURE_MMX) {
        printf("\t%s\t_CPU_FEATURE_MMX\n",
               avail & _CPU_FEATURE_MMX ? "yes" : "no");
    }
    if (mask & _CPU_FEATURE_SSE) {
        printf("\t%s\t_CPU_FEATURE_SSE\n",
               avail & _CPU_FEATURE_SSE ? "yes" : "no");
    }
    if (mask & _CPU_FEATURE_SSE2) {
        printf("\t%s\t_CPU_FEATURE_SSE2\n",
               avail & _CPU_FEATURE_SSE2 ? "yes" : "no");
    }
    if (mask & _CPU_FEATURE_3DNOW) {
        printf("\t%s\t_CPU_FEATURE_3DNOW\n",
               avail & _CPU_FEATURE_3DNOW ? "yes" : "no");
    }
}

void main(void)
{
    _p_info info;

    _cpuid(&info);

    printf("v_name:\t\t%s\n", info.v_name);
    printf("model:\t\t%s\n", info.model_name);
    printf("family:\t\t%d\n", info.family);
    printf("model:\t\t%d\n", info.model);
    printf("stepping:\t%d\n", info.stepping);
    printf("feature:\t%08x\n", info.feature);
    expand(info.feature, info.checks);
    printf("os_support:\t%08x\n", info.os_support);
    expand(info.os_support, info.checks);
    printf("checks:\t\t%08x\n", info.checks);
}

now, i really want to call this entire C/C++ program from python.
how would i go about this?

thanks!

EDIT: i'm using the microsoft c++ compilers, plus python 3.1.1.

pcmattman · Post by **pcmattman** » Wed Feb 10, 2010 11:24 pm

First hit on Google is the Python website.

Basically, you'll need to compile a shared object (DLL, .so) and import it. You may also need extra exposed symbols in the object.

redoktober · Post by **redoktober** » Thu Feb 11, 2010 2:48 am

okay.
now, basically, i have to recompile my C code as a DLL, and then call it using python's call interface.
i checked out the Python docs, but for some weird reason, i couldn't make head or tail of it.

do you think it's possible to like, compile MASM code into a DLL, and then have Python call it?

thanks!

MasterLee · Post by **MasterLee** » Thu Feb 11, 2010 3:59 am

Look at the follwing page:
http://docs.python.org/library/ctypes.html
That should help

Thomas · Post by **Thomas** » Fri Feb 12, 2010 6:43 am

redoktober wrote: do you think it's possible to like, compile MASM code into a DLL

.Short answer : yes.
--Thomas

redoktober · Post by **redoktober** » Mon Feb 15, 2010 12:47 am

ah....now this is gonna be super

thanks, guys!

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