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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Platform specific code to invoke XPCOM methods on native objects */
#include "xptcprivate.h"
// Remember that these 'words' are 32bit DWORDS
static uint32_t
invoke_count_words(uint32_t paramCount, nsXPTCVariant* s)
{
uint32_t result = 0;
for(uint32_t i = 0; i < paramCount; i++, s++)
{
if(s->IsPtrData())
{
result++;
continue;
}
switch(s->type)
{
case nsXPTType::T_I8 :
case nsXPTType::T_I16 :
case nsXPTType::T_I32 :
result++;
break;
case nsXPTType::T_I64 :
result+=2;
break;
case nsXPTType::T_U8 :
case nsXPTType::T_U16 :
case nsXPTType::T_U32 :
result++;
break;
case nsXPTType::T_U64 :
result+=2;
break;
case nsXPTType::T_FLOAT :
result++;
break;
case nsXPTType::T_DOUBLE :
result+=2;
break;
case nsXPTType::T_BOOL :
case nsXPTType::T_CHAR :
case nsXPTType::T_WCHAR :
result++;
break;
default:
// all the others are plain pointer types
result++;
break;
}
}
return result;
}
static void
invoke_copy_to_stack(uint32_t* d, uint32_t paramCount, nsXPTCVariant* s)
{
for(uint32_t i = 0; i < paramCount; i++, d++, s++)
{
if(s->IsPtrData())
{
*((void**)d) = s->ptr;
continue;
}
switch(s->type)
{
case nsXPTType::T_I8 : *((int8_t*) d) = s->val.i8; break;
case nsXPTType::T_I16 : *((int16_t*) d) = s->val.i16; break;
case nsXPTType::T_I32 : *((int32_t*) d) = s->val.i32; break;
case nsXPTType::T_I64 : *((int64_t*) d) = s->val.i64; d++; break;
case nsXPTType::T_U8 : *((uint8_t*) d) = s->val.u8; break;
case nsXPTType::T_U16 : *((uint16_t*)d) = s->val.u16; break;
case nsXPTType::T_U32 : *((uint32_t*)d) = s->val.u32; break;
case nsXPTType::T_U64 : *((uint64_t*)d) = s->val.u64; d++; break;
case nsXPTType::T_FLOAT : *((float*) d) = s->val.f; break;
case nsXPTType::T_DOUBLE : *((double*) d) = s->val.d; d++; break;
case nsXPTType::T_BOOL : *((bool*) d) = s->val.b; break;
case nsXPTType::T_CHAR : *((char*) d) = s->val.c; break;
case nsXPTType::T_WCHAR : *((wchar_t*) d) = s->val.wc; break;
default:
// all the others are plain pointer types
*((void**)d) = s->val.p;
break;
}
}
}
extern "C"
struct my_params_struct {
nsISupports* that;
uint32_t Index;
uint32_t Count;
nsXPTCVariant* params;
uint32_t fn_count;
uint32_t fn_copy;
};
XPTC_PUBLIC_API(nsresult)
XPTC_InvokeByIndex(nsISupports* that, uint32_t methodIndex,
uint32_t paramCount, nsXPTCVariant* params)
{
uint32_t result;
struct my_params_struct my_params;
my_params.that = that;
my_params.Index = methodIndex;
my_params.Count = paramCount;
my_params.params = params;
my_params.fn_copy = (uint32_t) &invoke_copy_to_stack;
my_params.fn_count = (uint32_t) &invoke_count_words;
/* This is to call a given method of class that.
* The parameters are in params, the number is in paramCount.
* The routine will issue calls to count the number of words
* required for argument passing and to copy the arguments to
* the stack.
* Since APCS passes the first 3 params in r1-r3, we need to
* load the first three words from the stack and correct the stack
* pointer (sp) in the appropriate way. This means:
*
* 1.) more than 3 arguments: load r1-r3, correct sp and remember No.
* of bytes left on the stack in r4
*
* 2.) <= 2 args: load r1-r3 (we won't be causing a stack overflow I hope),
* restore sp as if nothing had happened and set the marker r4 to zero.
*
* Afterwards sp will be restored using the value in r4 (which is not a temporary register
* and will be preserved by the function/method called according to APCS [ARM Procedure
* Calling Standard]).
*
* !!! IMPORTANT !!!
* This routine makes assumptions about the vtable layout of the c++ compiler. It's implemented
* for arm-linux GNU g++ >= 2.8.1 (including egcs and gcc-2.95.[1-3])!
*
*/
__asm__ __volatile__(
"ldr r1, [%1, #12] \n\t" /* prepare to call invoke_count_words */
"ldr ip, [%1, #16] \n\t" /* r0=paramCount, r1=params */
"ldr r0, [%1, #8] \n\t"
"mov lr, pc \n\t" /* call it... */
"mov pc, ip \n\t"
"mov r4, r0, lsl #2 \n\t" /* This is the amount of bytes needed. */
"sub sp, sp, r4 \n\t" /* use stack space for the args... */
"mov r0, sp \n\t" /* prepare a pointer an the stack */
"ldr r1, [%1, #8] \n\t" /* =paramCount */
"ldr r2, [%1, #12] \n\t" /* =params */
"ldr ip, [%1, #20] \n\t" /* =invoke_copy_to_stack */
"mov lr, pc \n\t" /* copy args to the stack like the */
"mov pc, ip \n\t" /* compiler would. */
"ldr r0, [%1] \n\t" /* =that */
"ldr r1, [r0, #0] \n\t" /* get that->vtable offset */
"ldr r2, [%1, #4] \n\t"
"add r2, r1, r2, lsl #3\n\t" /* a vtable_entry(x)=8 + (8 bytes * x) */
"add r2, r2, #8 \n\t" /* with this compilers */
"ldr r3, [r2] \n\t" /* get virtual offset from vtable */
"mov r3, r3, lsl #16 \n\t"
"add r0, r0, r3, asr #16\n\t"
"ldr ip, [r2, #4] \n\t" /* get method address from vtable */
"cmp r4, #12 \n\t" /* more than 3 arguments??? */
"ldmgtia sp!, {r1, r2, r3}\n\t" /* yes: load arguments for r1-r3 */
"subgt r4, r4, #12 \n\t" /* and correct the stack pointer */
"ldmleia sp, {r1, r2, r3}\n\t" /* no: load r1-r3 from stack */
"addle sp, sp, r4 \n\t" /* and restore stack pointer */
"movle r4, #0 \n\t" /* a mark for restoring sp */
"mov lr, pc \n\t" /* call mathod */
"mov pc, ip \n\t"
"add sp, sp, r4 \n\t" /* restore stack pointer */
"mov %0, r0 \n\t" /* the result... */
: "=r" (result)
: "r" (&my_params)
: "r0", "r1", "r2", "r3", "r4", "ip", "lr"
);
return result;
}
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