Custom Health ISA Extension (Version 1)

This project is a custom Instruction Set Architecture (ISA) extension based on RISC-V It adds health-related functionality such as height, weight, BMI, and BMR (Basal Metabolic Rate) calculations, using custom instructions implemented in Verilog.

📌 Version 1 Features

Each MEM[index] represents a user record, containing:

• Height (in centimeters)
• Weight (in kilograms)
• BMI (Body Mass Index)
• BMR (Basal Metabolic Rate)

Supported Instructions

Instruction	Description
SET_HEIGHT Rn, value	Set user height in centimeters
SET_WEIGHT Rn, value	Set user weight in kilograms
CALC_BMI Rn	Calculate BMI = weight / (height in m)^2
CALC_BMR Rn, gender, age	Calculate BMR using Mifflin-St Jeor Equation

Rn specifies the user index (i.e., MEM[ Rn ])

🔧 Instruction Format Design

• This custom ISA extension includes two types of instructions: I-type for setting user data, and R-type for computing results. All data is stored in memory where each MEM[user_index] holds a pair of values: height and weight.

🏗️ Memory Structure

MEM[user_index] = {
  height (cm),   // 32-bit
  weight (kg)    // 32-bit
}

Instruction	Type	Opcode（7-bit）
SET_HEIGHT	I-type	0001011
SET_WEIGHT	I-type	0001011
CALC_BMI	R-type	0001101
CALC_BMR	R-type	0001110

📘 I-type Instructions: SET_HEIGHT, SET_WEIGHT

• Used to directly set height or weight for a user. | 31–20 | 19–15 | 14–12 | 11–7 | 6–0 | | imm | rs1 | funct3| rd | opcode |
• rd: user index → selects MEM[user_index]
• imm: 12-bit immediate height or weight value
• funct3: field selector: 0 = height, 1 = weight
• MEM[rd] = value stored in rs1 + imm

SET_HEIGHT x1, 180  // Set height = 180 cm for MEM[x1]
SET_WEIGHT x1, 75   // Set weight = 75 kg for MEM[x1]

📘 R-type Instructions: CALC_BMI, CALC_BMR

• Used to compute BMI or BMR from the user's stored height and weight. The result is written into rs2. | 31–25 | 24–20 | 19–15 | 14–12 | 11–7 | 6–0 | | funct7 | rs2 | rs1 | funct3| rd | opcode |
• rs1: user index → source of height/weight
• rs2: destination register to hold the result
• rd: operation selector
• funct7: used to encode additional parameters:
• For BMR: [6] = gender (0=female, 1=male), [5:0] = age (0–63)

CALC_BMI x2, x1         // Compute BMI for user x1, store result in x2
CALC_BMR x2, x1, M25    // Compute BMR for user x1 (male, age 25), store result in x2

In BMR instruction, funct7 = 0b1_011001 (gender=1, age=25)