ram: Enable optional user-provided name for power rails

[tnguy19]

Summary

Allow users to change the names of power rails or leave as default (power_net=VDD, ground_net=VSS). README.md is also updated to include information on this change

Type of Change

• New feature
• Documentation update

Impact

Allow user-defined name for power rails

Verification

• I have verified that the local build succeeds (./etc/Build.sh).
• I have run the relevant tests and they pass.
• My code follows the repository's formatting guidelines.
• I have signed my commits (DCO).

Related Issues

Fixes #10563

@rovinski

[gemini-code-assist]

Code Review

This pull request adds support for custom power and ground net names in the RAM generator by introducing the optional -power_net_name and -ground_net_name arguments (defaulting to VDD and VSS). These parameters are propagated from the TCL interface down to the C++ implementation. Feedback on the changes suggests adding defensive checks in the C++ code to handle null or empty net names and to look up existing nets before creation, preventing potential segmentation faults.

[gemini-code-assist]

To prevent potential crashes (segmentation faults) if power_net_name or ground_net_name are null/empty, or if the nets already exist in the block (in which case dbNet::create returns nullptr), we should defensively check for null/empty names, try to find the existing nets first, and verify that the nets were successfully retrieved or created before using them.

  if (power_net_name == nullptr || power_net_name[0] == '\0') {
    power_net_name = "VDD";
  }
  if (ground_net_name == nullptr || ground_net_name[0] == '\0') {
    ground_net_name = "VSS";
  }

  auto power_net = block_->findNet(power_net_name);
  if (!power_net) {
    power_net = dbNet::create(block_, power_net_name);
  }
  auto ground_net = block_->findNet(ground_net_name);
  if (!ground_net) {
    ground_net = dbNet::create(block_, ground_net_name);
  }

  if (!power_net) {
    logger_->error(RAM, 38, "Failed to find or create power net: {}", power_net_name);
  }
  if (!ground_net) {
    logger_->error(RAM, 39, "Failed to find or create ground net: {}", ground_net_name);
  }

[tnguy19]

Safety checks are added in 9639564