Use conditional dependencies in riscv-rt depending on base extension

Author: romancardenas

riscv-rt/Cargo.toml

@@ -25,7 +25,22 @@ riscv-target-parser = { path = "../riscv-target-parser", version = "0.1.0" }
 [dependencies]
 riscv = { path = "../riscv", version = "0.12.0" }
 riscv-pac = { path = "../riscv-pac", version = "0.2.0" }
-riscv-rt-macros = { path = "macros", version = "0.2.2" }
+
+# For RV32I targets
+[target.'cfg(all(target_arch = "riscv32", riscvi))'.dependencies]
+riscv-rt-macros = { path = "macros", version = "0.3.0", features = ["riscv32i"] }
+# For RV32E targets (not that, in case of collision, RV32I has precedence over RV32E)
+[target.'cfg(all(target_arch = "riscv32", not(riscvi), riscve))'.dependencies]
+riscv-rt-macros = { path = "macros", version = "0.3.0", features = ["riscv32e"] }
+# For RV64I targets
+[target.'cfg(all(target_arch = "riscv64", riscvi))'.dependencies]
+riscv-rt-macros = { path = "macros", version = "0.3.0", features = ["riscv64i"] }
+# For RV64E targets (not that, in case of collision, RV64I has precedence over RV64E)
+[target.'cfg(all(target_arch = "riscv64", not(riscvi), riscve))'.dependencies]
+riscv-rt-macros = { path = "macros", version = "0.3.0", features = ["riscv64e"] }
+# For documentations, RV64I is the default
+[target.'cfg(not(any(target_arch = "riscv32", target_arch = "riscv64")))'.dependencies]
+riscv-rt-macros = { path = "macros", version = "0.3.0", features = ["riscv64i"] }
 
 [dev-dependencies]
 panic-halt = "1.0.0"

riscv-rt/macros/Cargo.toml

@@ -10,7 +10,7 @@ keywords = ["riscv", "runtime", "startup"]
 license = "MIT OR Apache-2.0"
 name = "riscv-rt-macros"
 repository = "https://github.com/rust-embedded/riscv"
-version = "0.2.2"
+version = "0.3.0"
 edition = "2021"
 
 [lib]
@@ -25,3 +25,7 @@ syn = { version = "2.0", features = ["extra-traits", "full"] }
 s-mode = []
 v-trap = []
 u-boot = []
+riscv32i = []
+riscv32e = []
+riscv64i = []
+riscv64e = []

riscv-rt/macros/build.rs

@@ -0,0 +1,20 @@
+use std::env;
+
+fn main() {
+    let features: Vec<String> = env::vars()
+        .filter_map(|(key, _)| {
+            if key.starts_with("CARGO_FEATURE_RISCV") {
+                Some(key)
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    if features.len() != 1 {
+        panic!(
+            "Exactly one RISC-V Base Extension feature must be enabled. Provided: {:?}",
+            features
+        );
+    }
+}