зеркало из https://github.com/mozilla/gecko-dev.git
Bug 532198 - Reimplement xptcinvoke for arm/linux in C [r=Jacob.Bramley, r=vladimir, sr=benjamin]
--HG-- extra : rebase_source : 683a17a26c486d6f6bf376ff93fb8a0567a8ab47
This commit is contained in:
Mike Hommey
Родитель
dc71114cae
Коммит
fdb8d0cadf
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@ -20,6 +20,7 @@
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Mike Hommey <mh@glandium.org>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either of the GNU General Public License Version 2 or later (the "GPL"),
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@ -43,84 +44,54 @@
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#error "This code is for Linux ARM only. Check that it works on your system, too.\nBeware that this code is highly compiler dependent."
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#endif
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/* Note that we give a "worst case" estimate of how much stack _might_ be
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* needed (for __ARM_EABI__), rather than the real count - this should be safe */
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#ifdef __ARM_EABI__
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#define DOUBLEWORD_ALIGN(p) ((PRUint32 *)((((PRUint32)(p)) + 7) & 0xfffffff8))
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#define VAR_STACK_SIZE_64 3
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#else
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#define DOUBLEWORD_ALIGN(p) (p)
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#define VAR_STACK_SIZE_64 2
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#endif
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// Remember that these 'words' are 32bit DWORDS
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static PRUint32
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invoke_count_words(PRUint32 paramCount, nsXPTCVariant* s)
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/* This function copies a 64-bits word from dw to the given pointer in
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* a buffer delimited by start and end, possibly wrapping around the
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* buffer boundaries, and/or properly aligning the data at 64-bits word
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* boundaries (for EABI).
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* start and end are both assumed to be 64-bits aligned.
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* Returns a pointer to the second 32-bits word copied (to accomodate
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* the invoke_copy_to_stack loop).
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*/
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static PRUint32 *
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copy_double_word(PRUint32 *start, PRUint32 *current, PRUint32 *end, PRUint64 *dw)
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{
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PRUint32 result = 0;
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for(PRUint32 i = 0; i < paramCount; i++, s++)
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{
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if(s->IsPtrData())
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{
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result++;
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continue;
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}
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switch(s->type)
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{
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case nsXPTType::T_I8 :
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case nsXPTType::T_I16 :
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case nsXPTType::T_I32 :
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result++;
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break;
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case nsXPTType::T_I64 :
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result+=VAR_STACK_SIZE_64;
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break;
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case nsXPTType::T_U8 :
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case nsXPTType::T_U16 :
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case nsXPTType::T_U32 :
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result++;
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break;
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case nsXPTType::T_U64 :
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result+=VAR_STACK_SIZE_64;
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break;
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case nsXPTType::T_FLOAT :
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result++;
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break;
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case nsXPTType::T_DOUBLE :
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result+=VAR_STACK_SIZE_64;
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break;
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case nsXPTType::T_BOOL :
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case nsXPTType::T_CHAR :
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case nsXPTType::T_WCHAR :
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result++;
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break;
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default:
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// all the others are plain pointer types
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result++;
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break;
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}
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}
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#ifdef __ARM_EABI__
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/* Ensure stack is always aligned to doubleword boundary; we take 3 words
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* off the stack to r1-r3 later, so it must always be on _odd_ word
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* boundary after this */
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if (result % 2 == 0)
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result++;
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/* Aligning the pointer for EABI */
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current = (PRUint32 *)(((PRUint32)current + 7) & ~7);
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/* Wrap when reaching the end of the buffer */
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if (current == end) current = start;
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#else
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/* On non-EABI, 64-bits values are not aligned and when we reach the end
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* of the buffer, we need to write half of the data at the end, and the
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* other half at the beginning. */
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if (current == end - 1) {
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*current = ((PRUint32*)dw)[0];
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*start = ((PRUint32*)dw)[1];
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return start;
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}
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#endif
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return result;
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*((PRUint64*) current) = *dw;
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return current + 1;
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}
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static void
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invoke_copy_to_stack(PRUint32* d, PRUint32 paramCount, nsXPTCVariant* s)
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invoke_copy_to_stack(PRUint32* stk, PRUint32 *end,
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PRUint32 paramCount, nsXPTCVariant* s)
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{
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/* The stack buffer is 64-bits aligned. The end argument points to its end.
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* The caller is assumed to create a stack buffer of at least four 32-bits
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* words.
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* We use the last three 32-bit words to store the values for r1, r2 and r3
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* for the method call, i.e. the first words for arguments passing.
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*/
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PRUint32 *d = end - 3;
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for(PRUint32 i = 0; i < paramCount; i++, d++, s++)
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{
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/* Wrap when reaching the end of the stack buffer */
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if (d == end) d = stk;
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NS_ASSERTION(d >= stk && d < end,
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"invoke_copy_to_stack is copying outside its given buffer");
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if(s->IsPtrData())
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{
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*((void**)d) = s->ptr;
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@ -134,16 +105,19 @@ invoke_copy_to_stack(PRUint32* d, PRUint32 paramCount, nsXPTCVariant* s)
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case nsXPTType::T_I8 : *((PRInt32*) d) = s->val.i8; break;
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case nsXPTType::T_I16 : *((PRInt32*) d) = s->val.i16; break;
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case nsXPTType::T_I32 : *((PRInt32*) d) = s->val.i32; break;
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case nsXPTType::T_I64 : d = DOUBLEWORD_ALIGN(d);
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*((PRInt64*) d) = s->val.i64; d++; break;
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case nsXPTType::T_I64 :
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d = copy_double_word(stk, d, end, (PRUint64 *)&s->val.i64);
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break;
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case nsXPTType::T_U8 : *((PRUint32*)d) = s->val.u8; break;
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case nsXPTType::T_U16 : *((PRUint32*)d) = s->val.u16; break;
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case nsXPTType::T_U32 : *((PRUint32*)d) = s->val.u32; break;
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case nsXPTType::T_U64 : d = DOUBLEWORD_ALIGN(d);
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*((PRUint64*)d) = s->val.u64; d++; break;
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case nsXPTType::T_U64 :
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d = copy_double_word(stk, d, end, (PRUint64 *)&s->val.u64);
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break;
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case nsXPTType::T_FLOAT : *((float*) d) = s->val.f; break;
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case nsXPTType::T_DOUBLE : d = DOUBLEWORD_ALIGN(d);
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*((double*) d) = s->val.d; d++; break;
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case nsXPTType::T_DOUBLE :
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d = copy_double_word(stk, d, end, (PRUint64 *)&s->val.d);
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break;
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case nsXPTType::T_BOOL : *((PRInt32*) d) = s->val.b; break;
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case nsXPTType::T_CHAR : *((PRInt32*) d) = s->val.c; break;
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case nsXPTType::T_WCHAR : *((PRInt32*) d) = s->val.wc; break;
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@ -155,48 +129,27 @@ invoke_copy_to_stack(PRUint32* d, PRUint32 paramCount, nsXPTCVariant* s)
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}
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}
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extern "C" {
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struct my_params_struct {
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nsISupports* that;
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PRUint32 Index;
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PRUint32 Count;
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nsXPTCVariant* params;
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PRUint32 fn_count;
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PRUint32 fn_copy;
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};
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}
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typedef PRUint32 (*vtable_func)(nsISupports *, PRUint32, PRUint32, PRUint32);
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EXPORT_XPCOM_API(nsresult)
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NS_InvokeByIndex(nsISupports* that, PRUint32 methodIndex,
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PRUint32 paramCount, nsXPTCVariant* params)
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{
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PRUint32 result;
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struct my_params_struct my_params;
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my_params.that = that;
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my_params.Index = methodIndex;
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my_params.Count = paramCount;
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my_params.params = params;
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my_params.fn_copy = (PRUint32) &invoke_copy_to_stack;
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my_params.fn_count = (PRUint32) &invoke_count_words;
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/* This is to call a given method of class that.
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* The parameters are in params, the number is in paramCount.
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* The routine will issue calls to count the number of words
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* required for argument passing and to copy the arguments to
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* the stack.
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* Since APCS passes the first 3 params in r1-r3, we need to
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* load the first three words from the stack and correct the stack
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* pointer (sp) in the appropriate way. This means:
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*
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* 1.) more than 3 arguments: load r1-r3, correct sp and remember No.
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* of bytes left on the stack in r4
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*
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* 2.) <= 2 args: load r1-r3 (we won't be causing a stack overflow I hope),
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* restore sp as if nothing had happened and set the marker r4 to zero.
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*
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* Afterwards sp will be restored using the value in r4 (which is not a temporary register
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* and will be preserved by the function/method called according to APCS [ARM Procedure
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* Calling Standard]).
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* ACPS passes the first 3 params in r1-r3 (with exceptions for 64-bits
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* arguments), and the remaining goes onto the stack.
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* We allocate a buffer on the stack for a "worst case" estimate of how much
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* stack might be needed for EABI, i.e. twice the number of parameters.
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* The end of this buffer will be used to store r1 to r3, so that the start
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* of the stack is the remaining parameters.
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* The magic here is to call the method with "that" and three 32-bits
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* arguments corresponding to r1-r3, so that the compiler generates the
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* proper function call. The stack will also contain the remaining arguments.
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*
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* !!! IMPORTANT !!!
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* This routine makes assumptions about the vtable layout of the c++ compiler. It's implemented
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@ -204,45 +157,21 @@ NS_InvokeByIndex(nsISupports* that, PRUint32 methodIndex,
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*
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*/
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__asm__ __volatile__(
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"ldr r1, [%1, #12] \n\t" /* prepare to call invoke_count_words */
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"ldr ip, [%1, #16] \n\t" /* r0=paramCount, r1=params */
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"ldr r0, [%1, #8] \n\t"
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"mov lr, pc \n\t" /* call it... */
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"mov pc, ip \n\t"
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"mov r4, r0, lsl #2 \n\t" /* This is the amount of bytes needed. */
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"sub sp, sp, r4 \n\t" /* use stack space for the args... */
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"mov r0, sp \n\t" /* prepare a pointer an the stack */
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"ldr r1, [%1, #8] \n\t" /* =paramCount */
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"ldr r2, [%1, #12] \n\t" /* =params */
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"ldr ip, [%1, #20] \n\t" /* =invoke_copy_to_stack */
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"mov lr, pc \n\t" /* copy args to the stack like the */
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"mov pc, ip \n\t" /* compiler would. */
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"ldr r0, [%1] \n\t" /* =that */
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"ldr r1, [r0, #0] \n\t" /* get that->vtable offset */
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"ldr r2, [%1, #4] \n\t"
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"mov r2, r2, lsl #2 \n\t" /* a vtable_entry(x)=8 + (4 bytes * x) */
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register vtable_func *vtable, func;
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register int base_size = (paramCount > 1) ? paramCount : 2;
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PRUint32 *stack_space = (PRUint32 *) __builtin_alloca(base_size * 8);
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invoke_copy_to_stack(stack_space, &stack_space[base_size * 2],
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paramCount, params);
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vtable = *reinterpret_cast<vtable_func **>(that);
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#if defined(__GXX_ABI_VERSION) && __GXX_ABI_VERSION >= 100 /* G++ V3 ABI */
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"ldr ip, [r1, r2] \n\t" /* get method adress from vtable */
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func = vtable[methodIndex];
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#else /* non G++ V3 ABI */
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"add r2, r2, #8 \n\t" /* with this compilers */
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"ldr ip, [r1, r2] \n\t" /* get method adress from vtable */
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func = vtable[2 + methodIndex];
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#endif
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"cmp r4, #12 \n\t" /* more than 3 arguments??? */
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"ldmgtia sp!, {r1, r2, r3}\n\t" /* yes: load arguments for r1-r3 */
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"subgt r4, r4, #12 \n\t" /* and correct the stack pointer */
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"ldmleia sp, {r1, r2, r3}\n\t" /* no: load r1-r3 from stack */
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"addle sp, sp, r4 \n\t" /* and restore stack pointer */
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"movle r4, #0 \n\t" /* a mark for restoring sp */
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"ldr r0, [%1, #0] \n\t" /* get (self) */
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"mov lr, pc \n\t" /* call mathod */
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"mov pc, ip \n\t"
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"add sp, sp, r4 \n\t" /* restore stack pointer */
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"mov %0, r0 \n\t" /* the result... */
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: "=r" (result)
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: "r" (&my_params), "m" (my_params)
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: "r0", "r1", "r2", "r3", "r4", "ip", "lr", "sp"
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);
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return result;
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return func(that, stack_space[base_size * 2 - 3],
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stack_space[base_size * 2 - 2],
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stack_space[base_size * 2 - 1]);
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}
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