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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"
// The purpose of NS_InvokeByIndex() is to map a platform
// independent call to the platform ABI. To do that,
// NS_InvokeByIndex() has to determine the method to call via vtable
// access. The parameters for the method are read from the
// nsXPTCVariant* and prepared for the native ABI.
//
// Prior to POWER8, all 64-bit Power ISA systems used ELF v1 ABI, found
// here:
// https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html
// and in particular:
// https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#FUNC-CALL
// Little-endian ppc64le, however, uses ELF v2 ABI, which is here:
// http://openpowerfoundation.org/wp-content/uploads/resources/leabi/leabi-20170510.pdf
// and in particular section 2.2, page 22. However, most big-endian ppc64
// systems still use ELF v1, so this file should support both.
// 7 integral parameters are passed in registers, not including |this|
// (i.e., r3-r10, with r3 being |this|).
const uint32_t GPR_COUNT = 7;
// 13 floating point parameters are passed in registers, either single or
// double precision (i.e., f1-f13).
const uint32_t FPR_COUNT = 13;
// Both ABIs use the same register assignment strategy, as per this
// example from V1 ABI section 3.2.3 and V2 ABI section 2.2.3.2 [page 43]:
//
// typedef struct {
// int a;
// double dd;
// } sparm;
// sparm s, t;
// int c, d, e;
// long double ld;
// double ff, gg, hh;
//
// x = func(c, ff, d, ld, s, gg, t, e, hh);
//
// Parameter Register Offset in parameter save area
// c r3 0-7 (not stored in parameter save area)
// ff f1 8-15 (not stored)
// d r5 16-23 (not stored)
// ld f2,f3 24-39 (not stored)
// s r8,r9 40-55 (not stored)
// gg f4 56-63 (not stored)
// t (none) 64-79 (stored in parameter save area)
// e (none) 80-87 (stored)
// hh f5 88-95 (not stored)
//
// i.e., each successive FPR usage skips a GPR, but not the other way around.
extern "C" void invoke_copy_to_stack(uint64_t* gpregs, double* fpregs,
uint32_t paramCount, nsXPTCVariant* s,
uint64_t* d)
{
uint32_t nr_gpr = 0u;
uint32_t nr_fpr = 0u;
uint64_t value = 0u;
for (uint32_t i = 0; i < paramCount; i++, s++) {
if (s->IsIndirect())
value = (uint64_t) &s->val;
else {
switch (s->type) {
case nsXPTType::T_FLOAT: break;
case nsXPTType::T_DOUBLE: break;
case nsXPTType::T_I8: value = s->val.i8; break;
case nsXPTType::T_I16: value = s->val.i16; break;
case nsXPTType::T_I32: value = s->val.i32; break;
case nsXPTType::T_I64: value = s->val.i64; break;
case nsXPTType::T_U8: value = s->val.u8; break;
case nsXPTType::T_U16: value = s->val.u16; break;
case nsXPTType::T_U32: value = s->val.u32; break;
case nsXPTType::T_U64: value = s->val.u64; break;
case nsXPTType::T_BOOL: value = s->val.b; break;
case nsXPTType::T_CHAR: value = s->val.c; break;
case nsXPTType::T_WCHAR: value = s->val.wc; break;
default: value = (uint64_t) s->val.p; break;
}
}
if (!s->IsIndirect() && s->type == nsXPTType::T_DOUBLE) {
if (nr_fpr < FPR_COUNT) {
fpregs[nr_fpr++] = s->val.d;
// Even if we have enough FPRs, still skip space in
// the parameter area if we ran out of placeholder GPRs.
if (nr_gpr < GPR_COUNT) {
nr_gpr++;
} else {
d++;
}
} else {
*((double *)d) = s->val.d;
d++;
}
}
else if (!s->IsIndirect() && s->type == nsXPTType::T_FLOAT) {
if (nr_fpr < FPR_COUNT) {
// Single-precision floats are passed in FPRs too.
fpregs[nr_fpr++] = s->val.f;
if (nr_gpr < GPR_COUNT) {
nr_gpr++;
} else {
d++;
}
} else {
#ifdef __LITTLE_ENDIAN__
*((float *)d) = s->val.f;
#else
// Big endian needs adjustment to point to the least
// significant word.
float* p = (float*)d;
p++;
*p = s->val.f;
#endif
d++;
}
}
else {
if (nr_gpr < GPR_COUNT) {
gpregs[nr_gpr++] = value;
} else {
*d++ = value;
}
}
}
}
EXPORT_XPCOM_API(nsresult)
NS_InvokeByIndex(nsISupports* that, uint32_t methodIndex, uint32_t paramCount,
nsXPTCVariant* params);
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