/*
 * Create trampolines to invoke arbitrary functions.
 * 
 * Copyright (C) Ximian Inc.
 * 
 * Author: Paolo Molaro (lupus@ximian.com)
 * 
 */

#include "config.h"
#include <stdlib.h>
#include <string.h>
#include "x86-codegen.h"
#include "mono/metadata/class.h"
#include "mono/metadata/tabledefs.h"
#include "mono/interpreter/interp.h"
#include "mono/metadata/appdomain.h"
#include "mono/metadata/marshal.h"

/*
 * The resulting function takes the form:
 * void func (void (*callme)(), void *retval, void *this_obj, stackval *arguments);
 */
#define FUNC_ADDR_POS	8
#define RETVAL_POS	12
#define THIS_POS	16
#define ARGP_POS	20
#define LOC_POS	-4

#define ARG_SIZE	sizeof (stackval)

MonoPIFunc
mono_create_trampoline (MonoMethodSignature *sig, gboolean string_ctor)
{
	unsigned char *p, *code_buffer;
	guint32 local_size = 0, stack_size = 0, code_size = 50;
	guint32 arg_pos, simpletype;
	int i, stringp;
	static GHashTable *cache = NULL;
	MonoPIFunc res;

	if (!cache) 
		cache = g_hash_table_new ((GHashFunc)mono_signature_hash, 
					  (GCompareFunc)mono_metadata_signature_equal);

	if ((res = (MonoPIFunc)g_hash_table_lookup (cache, sig)))
		return res;

	if (sig->hasthis) {
		stack_size += sizeof (gpointer);
		code_size += 5;
	}
	
	for (i = 0; i < sig->param_count; ++i) {
		if (sig->params [i]->byref) {
			stack_size += sizeof (gpointer);
			code_size += 20;
			local_size++;
			continue;
		}
		simpletype = sig->params [i]->type;
enum_calc_size:
		switch (simpletype) {
		case MONO_TYPE_BOOLEAN:
		case MONO_TYPE_CHAR:
		case MONO_TYPE_I1:
		case MONO_TYPE_U1:
		case MONO_TYPE_I2:
		case MONO_TYPE_U2:
		case MONO_TYPE_I4:
		case MONO_TYPE_U4:
		case MONO_TYPE_I:
		case MONO_TYPE_U:
		case MONO_TYPE_PTR:
		case MONO_TYPE_R4:
		case MONO_TYPE_SZARRAY:
		case MONO_TYPE_CLASS:
		case MONO_TYPE_OBJECT:
			stack_size += 4;
			code_size += i < 10 ? 5 : 8;
			break;
		case MONO_TYPE_VALUETYPE: {
			int size;
			if (sig->params [i]->data.klass->enumtype) {
				simpletype = sig->params [i]->data.klass->enum_basetype->type;
				goto enum_calc_size;
			}
			if ((size = mono_class_value_size (sig->params [i]->data.klass, NULL)) != 4) {
				stack_size += size + 3;
				stack_size &= ~3;
				code_size += 32;
			} else {
				stack_size += 4;
				code_size += i < 10 ? 5 : 8;
			}
			break;
		}
		case MONO_TYPE_STRING:
			stack_size += 4;
			code_size += 20;
			local_size++;
			break;
		case MONO_TYPE_I8:
			stack_size += 8;
			code_size += i < 10 ? 5 : 8;
			break;
		case MONO_TYPE_R8:
			stack_size += 8;
			code_size += i < 10 ? 7 : 10;
			break;
		default:
			g_error ("Can't trampoline 0x%x", sig->params [i]->type);
		}
	}
	/*
	 * FIXME: take into account large return values.
	 */

	code_buffer = p = alloca (code_size);

	/*
	 * Standard function prolog.
	 */
	x86_push_reg (p, X86_EBP);
	x86_mov_reg_reg (p, X86_EBP, X86_ESP, 4);
	/*
	 * We store some local vars here to handle string pointers.
	 * and align to 16 byte boundary...
	 */
	if (local_size) {
		x86_alu_reg_imm (p, X86_SUB, X86_ESP, local_size * 4);
		stack_size = (stack_size * local_size * 4) % 16;
	} else {
		stack_size = stack_size % 16;
	}
	if (stack_size)
		x86_alu_reg_imm (p, X86_SUB, X86_ESP, stack_size);

	/*
	 * EDX has the pointer to the args.
	 */
	x86_mov_reg_membase (p, X86_EDX, X86_EBP, ARGP_POS, 4);

	/*
	 * Push arguments in reverse order.
	 */
	stringp = 0;
	for (i = sig->param_count; i; --i) {
		arg_pos = ARG_SIZE * (i - 1);
		if (sig->params [i - 1]->byref) {
			x86_push_membase (p, X86_EDX, arg_pos);
			continue;
		}
		simpletype = sig->params [i - 1]->type;
enum_marshal:
		switch (simpletype) {
		case MONO_TYPE_BOOLEAN:
		case MONO_TYPE_I1:
		case MONO_TYPE_U1:
		case MONO_TYPE_I2:
		case MONO_TYPE_U2:
		case MONO_TYPE_CHAR:
		case MONO_TYPE_I4:
		case MONO_TYPE_U4:
		case MONO_TYPE_I:
		case MONO_TYPE_U:
		case MONO_TYPE_PTR:
		case MONO_TYPE_OBJECT:
			x86_push_membase (p, X86_EDX, arg_pos);
			break;
		case MONO_TYPE_R4:
			x86_alu_reg_imm (p, X86_SUB, X86_ESP, 4);
			x86_fld_membase (p, X86_EDX, arg_pos, TRUE);
			x86_fst_membase (p, X86_ESP, 0, FALSE, TRUE);
			break;
		case MONO_TYPE_CLASS:
			x86_push_membase (p, X86_EDX, arg_pos);
			break;
		case MONO_TYPE_SZARRAY:
			x86_push_membase (p, X86_EDX, arg_pos);
			break;
		case MONO_TYPE_VALUETYPE:
			if (!sig->params [i - 1]->data.klass->enumtype) {
				int size = mono_class_value_size (sig->params [i - 1]->data.klass, NULL);
				if (size == 4) {
					/* it's a structure that fits in 4 bytes, need to push the value pointed to */
					x86_mov_reg_membase (p, X86_EAX, X86_EDX, arg_pos, 4);
					x86_push_regp (p, X86_EAX);
				} else {
					int ss = size;
					ss += 3;
					ss &= ~3;

					x86_alu_reg_imm (p, X86_SUB, X86_ESP, ss);
					x86_push_imm (p, size);
					x86_push_membase (p, X86_EDX, arg_pos);
					x86_lea_membase (p, X86_EAX, X86_ESP, 2*4);
					x86_push_reg (p, X86_EAX);
					x86_mov_reg_imm (p, X86_EAX, memcpy);
					x86_call_reg (p, X86_EAX);
					x86_alu_reg_imm (p, X86_ADD, X86_ESP, 12);
				}
			} else {
				/* it's an enum value */
				simpletype = sig->params [i - 1]->data.klass->enum_basetype->type;
				goto enum_marshal;
			}
			break;
		case MONO_TYPE_STRING:
			x86_push_membase (p, X86_EDX, arg_pos);
			break;
		case MONO_TYPE_I8:
		case MONO_TYPE_U8:
		case MONO_TYPE_R8:
			x86_push_membase (p, X86_EDX, arg_pos + 4);
			x86_push_membase (p, X86_EDX, arg_pos);
			break;
		default:
			g_error ("Can't trampoline 0x%x", sig->params [i - 1]->type);
		}
	}

	if (sig->hasthis) {
		if (sig->call_convention != MONO_CALL_THISCALL) {
			x86_mov_reg_membase (p, X86_EDX, X86_EBP, THIS_POS, 4);
			x86_push_reg (p, X86_EDX);
		} else {
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, THIS_POS, 4);
		}
	}

	/* 
	 * Insert call to function 
	 */
	x86_mov_reg_membase (p, X86_EDX, X86_EBP, FUNC_ADDR_POS, 4);
	x86_call_reg (p, X86_EDX);

	/*
	 * Handle retval.
	 * Small integer and pointer values are in EAX.
	 * Long integers are in EAX:EDX.
	 * FP values are on the FP stack.
	 */

	if (sig->ret->byref || string_ctor) {
		x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
		x86_mov_regp_reg (p, X86_ECX, X86_EAX, 4);
	} else {
		simpletype = sig->ret->type;
	enum_retvalue:
		switch (simpletype) {
		case MONO_TYPE_BOOLEAN:
		case MONO_TYPE_I1:
		case MONO_TYPE_U1:
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_mov_regp_reg (p, X86_ECX, X86_EAX, 1);
			break;
		case MONO_TYPE_CHAR:
		case MONO_TYPE_I2:
		case MONO_TYPE_U2:
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_mov_regp_reg (p, X86_ECX, X86_EAX, 2);
			break;
		case MONO_TYPE_I4:
		case MONO_TYPE_U4:
		case MONO_TYPE_I:
		case MONO_TYPE_U:
		case MONO_TYPE_CLASS:
		case MONO_TYPE_OBJECT:
		case MONO_TYPE_SZARRAY:
		case MONO_TYPE_ARRAY:
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_mov_regp_reg (p, X86_ECX, X86_EAX, 4);
			break;
		case MONO_TYPE_STRING: 
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_mov_regp_reg (p, X86_ECX, X86_EAX, 4);
			break;
		case MONO_TYPE_R4:
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_fst_membase (p, X86_ECX, 0, FALSE, TRUE);
			break;
		case MONO_TYPE_R8:
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_fst_membase (p, X86_ECX, 0, TRUE, TRUE);
			break;
		case MONO_TYPE_I8:
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, RETVAL_POS, 4);
			x86_mov_regp_reg (p, X86_ECX, X86_EAX, 4);
			x86_mov_membase_reg (p, X86_ECX, 4, X86_EDX, 4);
			break;
		case MONO_TYPE_VALUETYPE:
			if (sig->ret->data.klass->enumtype) {
				simpletype = sig->ret->data.klass->enum_basetype->type;
				goto enum_retvalue;
			}
		case MONO_TYPE_VOID:
			break;
		default:
			g_error ("Can't handle as return value 0x%x", sig->ret->type);
		}
	}

	/*
	 * Standard epilog.
	 */
	x86_leave (p);
	x86_ret (p);

	g_assert (p - code_buffer < code_size);
	res = (MonoPIFunc)g_memdup (code_buffer, p - code_buffer);

	g_hash_table_insert (cache, sig, res);

	return res;
}

#define MINV_POS  (- sizeof (MonoInvocation))
#define STACK_POS (MINV_POS - sizeof (stackval) * sig->param_count)
#define OBJ_POS   8
#define TYPE_OFFSET (G_STRUCT_OFFSET (stackval, type))

/*
 * Returns a pointer to a native function that can be used to
 * call the specified method.
 * The function created will receive the arguments according
 * to the call convention specified in the method.
 * This function works by creating a MonoInvocation structure,
 * filling the fields in and calling ves_exec_method on it.
 * Still need to figure out how to handle the exception stuff
 * across the managed/unmanaged boundary.
 */
void *
mono_create_method_pointer (MonoMethod *method)
{
	MonoMethodSignature *sig;
	MonoJitInfo *ji;
	unsigned char *p, *code_buffer;
	gint32 local_size;
	gint32 stackval_pos, arg_pos = 8;
	int i, align;

	/*
	 * If it is a static P/Invoke method, we can just return the pointer
	 * to the method implementation.
	 */
	sig = method->signature;

	code_buffer = p = alloca (512); /* FIXME: check for overflows... */

	local_size = sizeof (MonoInvocation) + sizeof (stackval) * (sig->param_count + 1);
	stackval_pos = -local_size;

	/*
	 * Standard function prolog.
	 */
	x86_push_reg (p, X86_EBP);
	x86_mov_reg_reg (p, X86_EBP, X86_ESP, 4);
	x86_alu_reg_imm (p, X86_SUB, X86_ESP, local_size);

	/*
	 * Initialize MonoInvocation fields, first the ones known now.
	 */
	x86_mov_reg_imm (p, X86_EAX, 0);
	x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, ex)), X86_EAX, 4);
	x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, ex_handler)), X86_EAX, 4);
	x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, child)), X86_EAX, 4);
	x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, parent)), X86_EAX, 4);
	/*
	 * Set the method pointer.
	 */
	x86_mov_membase_imm (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, method)), (int)method, 4);
	/*
	 * Handle this.
	 */
	if (sig->hasthis) {
		if (sig->call_convention != MONO_CALL_THISCALL) {
			/*
			 * Grab it from the stack, otherwise it's already in ECX.
			 */
			x86_mov_reg_membase (p, X86_ECX, X86_EBP, OBJ_POS, 4);
			arg_pos += 4;
		}
		x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, obj)), X86_ECX, 4);
	}
	/*
	 * Handle the arguments. stackval_pos is the posset of the stackval array from EBP.
	 * arg_pos is the offset from EBP to the incoming arg on the stack.
	 * We just call stackval_from_data to handle all the (nasty) issues....
	 */
	x86_lea_membase (p, X86_EAX, X86_EBP, stackval_pos);
	x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, stack_args)), X86_EAX, 4);
	for (i = 0; i < sig->param_count; ++i) {
		x86_mov_reg_imm (p, X86_ECX, stackval_from_data);
		x86_lea_membase (p, X86_EDX, X86_EBP, arg_pos);
		x86_lea_membase (p, X86_EAX, X86_EBP, stackval_pos);
		x86_push_reg (p, X86_EDX);
		x86_push_reg (p, X86_EAX);
		x86_push_imm (p, sig->params [i]);
		x86_call_reg (p, X86_ECX);
		x86_alu_reg_imm (p, X86_SUB, X86_ESP, 12);
		stackval_pos += sizeof (stackval);
		arg_pos += mono_type_stack_size (sig->params [i], &align);
	}

	/*
	 * Handle the return value storage area.
	 */
	x86_lea_membase (p, X86_EAX, X86_EBP, stackval_pos);
	x86_mov_membase_reg (p, X86_EBP, (MINV_POS + G_STRUCT_OFFSET (MonoInvocation, retval)), X86_EAX, 4);

	/*
	 * Call the method.
	 */
	x86_lea_membase (p, X86_EAX, X86_EBP, MINV_POS);
	x86_push_reg (p, X86_EAX);
	x86_mov_reg_imm (p, X86_EDX, ves_exec_method);
	x86_call_reg (p, X86_EDX);

	/*
	 * Move the return value to the proper place.
	 */
	x86_lea_membase (p, X86_EAX, X86_EBP, stackval_pos);
	if (sig->ret->byref) {
		x86_mov_reg_membase (p, X86_EAX, X86_EAX, 0, 4);
	} else {
		int simpletype = sig->ret->type;	
	enum_retvalue:
		switch (sig->ret->type) {
		case MONO_TYPE_VOID:
			break;
		case MONO_TYPE_BOOLEAN:
			x86_mov_reg_membase (p, X86_EAX, X86_EAX, 0, 1);
			break;
		case MONO_TYPE_I4:
		case MONO_TYPE_U4:
		case MONO_TYPE_I:
		case MONO_TYPE_U:
		case MONO_TYPE_OBJECT:
		case MONO_TYPE_STRING:
		case MONO_TYPE_CLASS:
			x86_mov_reg_membase (p, X86_EAX, X86_EAX, 0, 4);
			break;
		case MONO_TYPE_I8:
			x86_mov_reg_membase (p, X86_EDX, X86_EAX, 4, 4);
			x86_mov_reg_membase (p, X86_EAX, X86_EAX, 0, 4);
			break;
		case MONO_TYPE_R8:
			x86_fld_membase (p, X86_EAX, 0, TRUE);
			break;
		case MONO_TYPE_VALUETYPE:
			if (sig->ret->data.klass->enumtype) {
				simpletype = sig->ret->data.klass->enum_basetype->type;
				goto enum_retvalue;
			}
			/* do nothing ? */
			break;
		default:
			g_error ("Type 0x%x not handled yet in thunk creation", sig->ret->type);
			break;
		}
	}
	
	/*
	 * Standard epilog.
	 */
	x86_leave (p);
	x86_ret (p);

	g_assert (p - code_buffer < 512);

	ji = g_new0 (MonoJitInfo, 1);
	ji->method = method;
	ji->code_size = p - code_buffer;
	ji->code_start = g_memdup (code_buffer, p - code_buffer);

	mono_jit_info_table_add (mono_root_domain, ji);

	return ji->code_start;
}