Diddy Kong Racing (the DavidSM64 decompilation, DavidSM64/Diddy-Kong-Racing)

In the US 1.0 version of Diddy Kong Racing, a race, challenge, or time trial starts its countdown at 80, and once the HUD signals the start each update takes the update rate off it; "Get Ready" shows while it reads 2 or more. A racer's first fresh press of A after the countdown drops below 80 decides its start boost. A press while the countdown reads 29 to 15 sets a boost timer of 4 up to 11 as the reading falls, half of 24 less the reading's excess over 14, rounded down (computed), and a press while it reads 14 or less sets 20 with a select sound; holding Z also counts a reading of 15 as 20. A first press while it reads 30 to 79 gives no boost and spends the chance. A Master CPU driver takes the start boost a human set, or 5 if none did, and an Expert one copies a human's if there is one. In the car's ground routine, while the boost timer is above 0 after the countdown, the throttle is held open and the factor the code calls traction, unless it's 0, becomes 2.0. Mario Kart 64 instead takes a press of A that begins within 8 race frame counts of its window opening (20 in Time Trials), while the kart's THROTTLE flag isn't already set, and every such start gets the Mushroom's boost timer, 80. dkr/start-boost

About: Diddy Kong Racing Rocket start

{
 "countdown": 80,
 "window-opens": 29,
 "best-from": 14,
 "best-boost": 20,
 "other-boosts": [
  4,
  11
 ],
 "forfeit-from": 79,
 "master-default": 5
}

The press test runs before the line that sets startInput in the same call, so a press at 29 or below still counts. boostType (small below 20, medium at 20) picks the boost's look; the lines read don't use it for speed. The countdown counts the update rate, which fb_update (src/video.c) returns as the number of video messages since the last frame, capped at 6; the decompilers' comment calls the default 2 "LOGIC_30FPS". At 2 a step, readings are even, so seven updates (14 down to 2) give the best boost; that isn't measured. normalise_time scales the boost timers by 5/6 on a PAL console. Holding Z is the code's Z_TRIG in the held input, read as is.

Cited by: Diddy Kong Racing, Rocket start

In the US 1.0 version of Diddy Kong Racing, a weapon balloon's type is set by its entry in the track's object list, with no roll: the code names five types, boost, missile, trap, shield, and magnet, which the decompilers' names for the all-balloons cheats pair with blue, red, green, yellow, and rainbow. A racer that touches a balloon takes its type. If the racer already held the same type with any left, the weapon's level rises by one, up to the third (level 2); otherwise it starts at the first. In a challenge the level stops at the second, and trap balloons start there; the Maximum Power-up cheat makes every pickup third-level, and CPU-driven boss vehicles collect none. The weapon and its quantity come from a table the game loads as an asset, two bytes for each type and level, so they aren't in the repo. A CPU racer's driving routine func_80042D20 can also raise a first-level pickup by one, on a percent chance from the AI behavior table. Mario Kart 64 instead picks an item box's item in Grand Prix from a 100-slot row for the driver's place. dkr/weapon-balloons

About: Diddy Kong Racing Item distribution

{
 "types": 5,
 "levels": 3,
 "challenge-levels": 2
}

unk209 & 1 is the flag the pickup sets and func_80042D20 clears. The percent chance interpolates between two values of the AI behavior table by var_t5, which counts the CPU racers ahead of this one; unk201 (a 30-count timer set elsewhere) must be 0. The same branch can, on another roll, change a CPU's balloon to the boost type when a human leads and fewer than three CPUs are ahead (L339-L342). The weapon enum names three Nitro, three magnet, and three shield levels, rockets, a homing rocket, a tripmine, an oil slick, and a bubble trap (src/racer.h#L84-L104); which type and level gives which weapon is in the asset table. A taken balloon regrows over 90 counts once the racer has moved 45 away.

Cited by: Diddy Kong Racing, Item distribution

In the US 1.0 version of Diddy Kong Racing, a car's power slide starts in its ground routine when R is held, the stick is past 15 either way, and the car is going forward faster than 3 (the code's velocity below -3). While R stays held the routine multiplies the top-speed value by 1.1. Letting go of R, or slowing to a velocity above -2, ends the slide and sets nothing else. During a slide the car update clamps the stick to 50 either way, quarters steering into the slide, and adds 60 toward it; holding the stick 26 or more against the slide adds the update rate to a count, and past 80 the car spins out and the slide ends. In an atlas search of src/, every write to the boost timer belongs to a zip pad, zipper, the start, a Nitro, a magnet, a plane trick, the loop-the-loop vehicle, or a boss, so a slide ends without a boost. Mario Kart 64 instead charges stages toward a mini-turbo while the stick counter-steers a drift. dkr/power-slide

About: Diddy Kong Racing Drift boost

{
 "slide-top-speed": 1.1,
 "start-stick": 15,
 "counter-stick": 26,
 "spin-out-after": 80
}

Forward is negative in the car's velocity: the throttle subtracts from it (L5519). The counter-steer count resets when the stick isn't held against the slide, so the 80 must be unbroken. The hovercraft and plane routines set drift_direction in their own code, not read here. racer_spinout_car is the decompilers' name.

Cited by: Diddy Kong Racing, Drift boost

In the US 1.0 version of Diddy Kong Racing, a zip-pad surface sets a racer's boost timer to 45 when it's at 0, in the car, hovercraft, and plane routines alike, and a ground zipper object sets 45 for a grounded racer within its radius whenever the timer is below 15. A Nitro sets 35, 55, or 75 at its first, second, and third level. In the car's ground routine, while the timer is above 0 after the countdown, the throttle is held open and the factor the code calls traction, unless it's 0, becomes 2.0. dkr/zip-pads

About: Diddy Kong Racing Boost pad

{
 "zip-pad": 45,
 "zipper-refresh-below": 15,
 "nitro": [
  35,
  55,
  75
 ]
}

The timer loses the update rate each update (src/racer.c#L5499), so at 2 a step, the rate the decompilers' comment calls the default, a zip pad lasts 23 updates (computed, not measured). normalise_time scales 45 to 37 on a PAL console. Releasing A before a boost sets an "empowered" flag in boostType (throttleReleased); the lines read use it to pick the boost's look, and its effect on speed isn't traced. The hovercraft also takes a boost from zipper objects on water (L1685-L1702), and the AI car routine has its own zip-pad test (L6531-L6533).

Cited by: Boost pad, Diddy Kong Racing