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/* $Id$ */

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#include "stdafx.h"

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#include "openttd.h"

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#include "variables.h"

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#include "macros.h"

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#include "oldpool.h"

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#include "newgrf_callbacks.h"

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#include "newgrf_spritegroup.h"

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#include "date.h"

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static void SpriteGroupPoolCleanBlock(uint start_item, uint end_item);

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static uint _spritegroup_count = 0;

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STATIC_OLD_POOL(SpriteGroup, SpriteGroup, 9, 250, NULL, SpriteGroupPoolCleanBlock)

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static void DestroySpriteGroup(SpriteGroup *group)

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{

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	/* Free dynamically allocated memory */

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	/* XXX Cast away the consts due to MSVC being buggy... */

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	switch (group->type) {

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		case SGT_REAL:

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			free((SpriteGroup**)group->g.real.loaded);

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			free((SpriteGroup**)group->g.real.loading);

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			break;

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		case SGT_DETERMINISTIC:

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			free(group->g.determ.adjusts);

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			free(group->g.determ.ranges);

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			break;

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		case SGT_RANDOMIZED:

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			free((SpriteGroup**)group->g.random.groups);

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			break;

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		default:

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			break;

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	}

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}

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static void SpriteGroupPoolCleanBlock(uint start_item, uint end_item)

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{

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	uint i;

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	for (i = start_item; i <= end_item; i++) {

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		DestroySpriteGroup(GetSpriteGroup(i));

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	}

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}

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/* Allocate a new SpriteGroup */

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SpriteGroup *AllocateSpriteGroup(void)

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{

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	/* This is totally different to the other pool allocators, as we never remove an item from the pool. */

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	if (_spritegroup_count == GetSpriteGroupPoolSize()) {

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		if (!AddBlockToPool(&_SpriteGroup_pool)) return NULL;

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	}

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	return GetSpriteGroup(_spritegroup_count++);

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}

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void InitializeSpriteGroupPool(void)

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{

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	CleanPool(&_SpriteGroup_pool);

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	_spritegroup_count = 0;

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}

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static inline uint32 GetVariable(const ResolverObject *object, byte variable, byte parameter, bool *available)

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{

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	/* Return common variables */

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	switch (variable) {

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		case 0x00: return max(_date - DAYS_TILL_ORIGINAL_BASE_YEAR, 0);

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		case 0x01: return clamp(_cur_year, ORIGINAL_BASE_YEAR, ORIGINAL_MAX_YEAR) - ORIGINAL_BASE_YEAR;

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		case 0x02: return _cur_month;

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		case 0x03: return _opt.landscape;

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		case 0x09: return _date_fract;

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		case 0x0A: return _tick_counter;

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		case 0x0C: return object->callback;

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		case 0x10: return object->callback_param1;

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		case 0x11: return 0;

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		case 0x18: return object->callback_param2;

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		case 0x1A: return UINT_MAX;

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		case 0x1B: return GB(_display_opt, 0, 6);

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		case 0x1C: return object->last_value;

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		case 0x20: return _opt.landscape == LT_HILLY ? _opt.snow_line : 0xFF;

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		/* Not a common variable, so evalute the feature specific variables */

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		default: return object->GetVariable(object, variable, parameter, available);

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	}

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}

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/* Evaluate an adjustment for a variable of the given size.

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* U is the unsigned type and S is the signed type to use. */

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template <typename U, typename S>

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static U EvalAdjustT(const DeterministicSpriteGroupAdjust *adjust, U last_value, uint32 value)

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{

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	value >>= adjust->shift_num;

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	value  &= adjust->and_mask;

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	if (adjust->type != DSGA_TYPE_NONE) value += (S)adjust->add_val;

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	switch (adjust->type) {

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		case DSGA_TYPE_DIV:  value /= (S)adjust->divmod_val; break;

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		case DSGA_TYPE_MOD:  value %= (U)adjust->divmod_val; break;

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		case DSGA_TYPE_NONE: break;

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	}

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	switch (adjust->operation) {

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		case DSGA_OP_ADD:  return last_value + value;

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		case DSGA_OP_SUB:  return last_value - value;

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		case DSGA_OP_SMIN: return min((S)last_value, (S)value);

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		case DSGA_OP_SMAX: return max((S)last_value, (S)value);

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		case DSGA_OP_UMIN: return min((U)last_value, (U)value);

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		case DSGA_OP_UMAX: return max((U)last_value, (U)value);

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		case DSGA_OP_SDIV: return (S)last_value / (S)value;

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		case DSGA_OP_SMOD: return (S)last_value % (S)value;

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		case DSGA_OP_UDIV: return (U)last_value / (U)value;

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		case DSGA_OP_UMOD: return (U)last_value % (U)value;

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		case DSGA_OP_MUL:  return last_value * value;

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		case DSGA_OP_AND:  return last_value & value;

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		case DSGA_OP_OR:   return last_value | value;

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		case DSGA_OP_XOR:  return last_value ^ value;

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		default:           return value;

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	}

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}

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static inline const SpriteGroup *ResolveVariable(const SpriteGroup *group, ResolverObject *object)

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{

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	static SpriteGroup nvarzero;

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	uint32 last_value = 0;

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	uint32 value = 0;

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	uint i;

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	object->scope = group->g.determ.var_scope;

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	for (i = 0; i < group->g.determ.num_adjusts; i++) {

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		DeterministicSpriteGroupAdjust *adjust = &group->g.determ.adjusts[i];

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		/* Try to get the variable. We shall assume it is available, unless told otherwise. */

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		bool available = true;

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		if (adjust->variable == 0x7E) {

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			ResolverObject subobject = *object;

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			const SpriteGroup *subgroup = Resolve(adjust->subroutine, &subobject);

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			if (subgroup == NULL || subgroup->type != SGT_CALLBACK) {

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				value = CALLBACK_FAILED;

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			} else {

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				value = subgroup->g.callback.result;

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			}

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		} else {

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			value = GetVariable(object, adjust->variable, adjust->parameter, &available);

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		}

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		if (!available) {

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			/* Unsupported property: skip further processing and return either

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			 * the group from the first range or the default group. */

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			return Resolve(group->g.determ.num_ranges > 0 ? group->g.determ.ranges[0].group : group->g.determ.default_group, object);

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		}

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		switch (group->g.determ.size) {

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			case DSG_SIZE_BYTE:  value = EvalAdjustT<uint8, int8>(adjust, last_value, value); break;

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			case DSG_SIZE_WORD:  value = EvalAdjustT<uint16, int16>(adjust, last_value, value); break;

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			case DSG_SIZE_DWORD: value = EvalAdjustT<uint32, int32>(adjust, last_value, value); break;

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			default: NOT_REACHED(); break;

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		}

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		last_value = value;

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	}

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	object->last_value = last_value;

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	if (group->g.determ.num_ranges == 0) {

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		/* nvar == 0 is a special case -- we turn our value into a callback result */

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		nvarzero.type = SGT_CALLBACK;

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		nvarzero.g.callback.result = GB(value, 0, 15);

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		return &nvarzero;

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	}

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	for (i = 0; i < group->g.determ.num_ranges; i++) {

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		if (group->g.determ.ranges[i].low <= value && value <= group->g.determ.ranges[i].high) {

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			return Resolve(group->g.determ.ranges[i].group, object);

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		}

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	}

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	return Resolve(group->g.determ.default_group, object);

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}

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static inline const SpriteGroup *ResolveRandom(const SpriteGroup *group, ResolverObject *object)

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{

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	uint32 mask;

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	byte index;

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	object->scope = group->g.random.var_scope;

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	if (object->trigger != 0) {

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		/* Handle triggers */

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		/* Magic code that may or may not do the right things... */

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		byte waiting_triggers = object->GetTriggers(object);

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		byte match = group->g.random.triggers & (waiting_triggers | object->trigger);

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		bool res;

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		res = (group->g.random.cmp_mode == RSG_CMP_ANY) ?

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			(match != 0) : (match == group->g.random.triggers);

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		if (res) {

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			waiting_triggers &= ~match;

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			object->reseed |= (group->g.random.num_groups - 1) << group->g.random.lowest_randbit;

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		} else {

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			waiting_triggers |= object->trigger;

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		}

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		object->SetTriggers(object, waiting_triggers);

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	}

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	mask  = (group->g.random.num_groups - 1) << group->g.random.lowest_randbit;

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	index = (object->GetRandomBits(object) & mask) >> group->g.random.lowest_randbit;

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	return Resolve(group->g.random.groups[index], object);

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}

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/* ResolverObject (re)entry point */

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const SpriteGroup *Resolve(const SpriteGroup *group, ResolverObject *object)

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{

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	/* We're called even if there is no group, so quietly return nothing */

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	if (group == NULL) return NULL;

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	switch (group->type) {

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		case SGT_REAL:          return object->ResolveReal(object, group);

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		case SGT_DETERMINISTIC: return ResolveVariable(group, object);

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		case SGT_RANDOMIZED:    return ResolveRandom(group, object);

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		default:                return group;

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	}

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}