Harvest Moon 64

References

1. ^In the US release, a crop is a run of tile numbers in groundObjectsInfo, each growth stage a dry tile followed by its watered twin. The watering can turns a waterable tile into the next number (dry soil into watered soil). Each night, updateGroundObjectsOvernight reads a flag byte per tile: a watered stage moves on to the next stage's dry tile, watered soil and a watered ripe crop go back to dry, and a dry stage stays where it is. So a crop grows one stage per watered day and a dry day doesn't count. Worked out from the table (computed), the watered days from sowing to ripe are: turnip 4, potato 6, strawberry 6, moondrop flower 6, cabbage 7, eggplant 7, pink cat mint 8, tomato 9, corn 13. Grass's stages aren't waterable and advance every night: 9 nights from seed.Codeharvestwhisperer/hm64-decomp
   How we know

   236    u8 playerInteractionFlags;
   

   47    { 0x07, 0x00, 0x00, GROUND_OBJECT_TILLABLE, 0x09 },
   ⋮
   49    { 0x07, 0x00, 0x00, GROUND_OBJECT_TILLABLE, 0x09 },
   

   1242                    currentGroundObject++;
   

   3096                temp2 = currentGroundObjectIndex + 1;
   

   171    { 0x06, 0x00, 0x00, GROUND_OBJECT_TILLABLE, 0x09 },
   172    { 0x06, 0x00, 0x00, GROUND_OBJECT_TILLABLE, 0x09 },
   173    { 0x06, 0x00, 0x00, GROUND_OBJECT_TILLABLE, 0x09 },
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   In the claim ledger

2. ^In the US release, each night the new day's weather is set before the crops update; then, if it is rain, updateCropsIfRain turns every waterable tile on the farm into its watered twin, as the watering can would, so a rainy day counts as watered. The greenhouse isn't touched.Codeharvestwhisperer/hm64-decomp
   How we know

   691    gWeather = gForecast;
   

   1473                        setFieldTile(FARM, groundObjectIndex + 1, j, i);
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   In the claim ledger

3. ^In the US release, the farm's overnight update has a rule for the night that starts a season (the day of the month is 1 by then). Summer turns sprouted-or-older turnips, potatoes, and cabbages into dead plants and their seed stages back into tilled soil. Autumn does the same to tomatoes, corn, moondrop flowers, and pink cat mint, and sends any spring seed stages to tilled soil. Winter clears dry tilled soil, weeds, eggplants at every stage, the dead plants, and the remaining seed stages to the bare tile. Spring turns grass back to cut grass and returns tilled soil to the bare tile when getRandomNumberInRange(0, 5) >= 3. Strawberries, whose seeds sow only in the greenhouse, appear in none of the lists, and the greenhouse loop has no season rule.Codeharvestwhisperer/hm64-decomp
   How we know

   1292                                case TURNIP_SPROUT_STAGE_1 ... TURNIP_RIPE_WATERED:
   

   1321                                case TOMATO_SPROUT_STAGE_1 ... TOMATO_RIPE_WATERED:
   

   1350                                case POTATO_DEAD ... EGGPLANT_RIPE_WATERED:
   

   1384    // greenhouse
   1385    for (i = 0; i < FIELD_HEIGHT; i++) {
   ⋮
   1389            currentGroundObject = greenhouseFieldTiles[i][j];
   ⋮
   1409                 greenhouseFieldTiles[i][j] = currentGroundObject;
   

   3486        groundObjectIndex = (gBaseMapIndex == GREENHOUSE) ? STRAWBERRY_PLANTED_STAGE_1 : INVALID_GROUND_OBJECT;
   

   700    updateGroundObjectsOvernight();
   

   2541        setClockNewDay(); 
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-25.

   In the claim ledger

4. ^In the US release, toolToFatigueScore gives each tool a stamina cost per charge level: the sickle and hoe 2, 4, and 6; the ax and hammer 1, 2, and 3; the watering can 1, 2, and 6; the milker, bell, brush, clippers, the seed bags, and grass seeds 1; the rest 0. Releasing B subtracts the cost from stamina. If it is raining or snowing, or the hour is before 6:00 or from 18:00, and the player isn't in the greenhouse, the same cost is added to fatigue (out of 100), or half of it once a life-event flag the decompilers name KAPPA_POWER_NUT_GIFT is set. Holding B raises the charge level each time a hold counter reaches 16, up to the tool's upgrade level, while stamina covers the next level's cost.Codeharvestwhisperer/hm64-decomp
   How we know

   291    { 2, 4, 6 },
   292    { 2, 4, 6 },
   

   61#define WATERING_CAN 5
   

   1635                if (((SUNNY < gWeather && gWeather < 4) || !(5 < gHour && gHour < 18)) && gBaseMapIndex != GREENHOUSE) {
   

   8#define SNOW 3
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   In the claim ledger

5. ^In the US release, going to bed refills stamina to its maximum and, unless fatigue is at 100, takes 2 points of fatigue off for each hour of sleep before 6:00, 3 with the cushion (life event HAVE_CUSHION): the hour taken is the bedtime, plus 24 if before 6:00, subtracted from 30. Staying up until 6:00 runs the next day's update by another path that doesn't touch stamina or fatigue. Food and drink add the item's stamina value and take off its fatigue value.Codeharvestwhisperer/hm64-decomp
   How we know

   2531                gPlayer.fatigueCounter += adjustValue(gPlayer.fatigueCounter, -((30 - tempTime) * 2), 100);
   

   3254                    handleExitLevel(8, END_OF_DAY_1);    
   

   61            handleExitLevel(1, END_OF_DAY_2);
   

   2600        startNewDay();
   

   1791            gPlayer.currentStamina += adjustValue(gPlayer.currentStamina, getItemStaminaIncreaseValue(gPlayer.heldItem), gMaximumStamina);
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   In the claim ledger

6. ^In the US release, a cow's milk size comes from its affection (0 to 255): small at 150 or less, medium from 151 to 220, large from 221, and golden for a cow whose milkType is 0, whatever its affection.Codeharvestwhisperer/hm64-decomp
   How we know

   428        if (gFarmAnimals[animalIndex].affection >= 221) {
   

   19#define MAX_AFFECTION 255
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   In the claim ledger

7. ^In the US release, adjustFarmAnimalAffection scales a change by an adult cow's condition: a happy cow's gains are doubled and a mad or sick cow's halved. Its loss branch negates the scaled amount, -(amount * 2) for mad and sick and -(amount / 2) for happy, and since the amount is already negative, the result is positive: a loss raises a mad, sick, or happy cow's affection, by twice or half the loss (computed). Leaving an adult cow outdoors on a rainy day can trigger this: updateFarmStatusRain makes it mad when getRandomNumberInRange(0, 3) returns 0 and then applies −20, or sick when getRandomNumberInRange(0, 7) returns 0 and then applies −30, and a cow already sick gets −20.Codeharvestwhisperer/hm64-decomp
   How we know

   353                        adjusted = (amount >= 0) ? (amount / 2) : -(amount * 2);
   ⋮
   361                        adjusted = (amount >= 0) ? (amount / 2) : -(amount * 2);
   

   402        gFarmAnimals[animalIndex].affection += adjustValue(gFarmAnimals[animalIndex].affection, adjusted, MAX_AFFECTION);
   

   275                gFarmAnimals[index].condition = condition;
   

   322                                setAnimalState(2, i, 0xFF, COW_MAD, 0);
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Checked by a second AI model, 2026-10-22.

   In the claim ledger