examples: check for tool availability before building

examples/common/build_ice40.sh

@@ -1,5 +1,11 @@
 #!/usr/bin/env bash
 set -euo pipefail
+source "$(dirname "$(readlink -f "$0")")/find_tool.sh"
+
+# Make sure tools are accessible
+YOSYS_CMD=$(find_tool yosys)
+NEXTPNR_ICE40_CMD=$(find_tool nextpnr-ice40)
+ICEPACK_CMD=$(find_tool icepack)
 
 # Generate Verilog source for Manta
 python3 -m manta gen manta.yaml manta.v
@@ -8,6 +14,6 @@ python3 -m manta gen manta.yaml manta.v
 rm -rf build/
 mkdir -p build/
 cd build
-$YOSYS -p 'synth_ice40 -top top_level -json top_level.json' ../top_level.sv
-$NEXTPNR_ICE40 --hx1k --json top_level.json --pcf ../top_level.pcf --asc top_level.asc
-$ICEPACK top_level.asc top_level.bin
+$YOSYS_CMD -p 'synth_ice40 -top top_level -json top_level.json' ../top_level.sv
+$NEXTPNR_ICE40_CMD --hx1k --json top_level.json --pcf ../top_level.pcf --asc top_level.asc
+$ICEPACK_CMD top_level.asc top_level.bin

examples/common/build_vivado.sh

@@ -1,33 +1,13 @@
 #!/usr/bin/env bash
 set -euo pipefail
+source "$(dirname "$(readlink -f "$0")")/find_tool.sh"
+
+# Make sure Vivado is accessible
+VIVADO_CMD=$(find_tool vivado)
 
 # Generate Verilog source for Manta
 python3 -m manta gen manta.yaml manta.v
 
-# Determine where Vivado is located - exactly one of PATH or $VIVADO must be available
-vivado_on_path=false
-vivado_env_set=false
-
-if command -v vivado &> /dev/null; then
-    vivado_on_path=true
-fi
-
-if [[ -v VIVADO ]]; then
-    vivado_env_set=true
-fi
-
-if $vivado_on_path && $vivado_env_set; then
-    echo "Error: Both \$VIVADO is set and 'vivado' is on PATH. Please use only one." >&2
-    exit 1
-elif $vivado_on_path; then
-    VIVADO_CMD="vivado"
-elif $vivado_env_set; then
-    VIVADO_CMD="$VIVADO"
-else
-    echo "Error: Vivado not found. Either set \$VIVADO environment variable or add 'vivado' to PATH." >&2
-    exit 1
-fi
-
 # Clean build/ directory, and run Vivado from within it
 rm -rf build/
 mkdir -p build/

examples/common/find_tool.sh

@@ -0,0 +1,32 @@
+# Find a tool binary from either the $PATH environment variable, or another
+# environment variable named after the tool (ie, $VIVADO or $YOSYS).
+# Usage: find_tool <tool_name>
+# The environment variable is the uppercased tool name, with any hyphens converted to underscores.
+# Prints the command to use, or exits with an error.
+find_tool() {
+    local tool="$1"
+    local env_var="${tool^^}"
+    env_var="${env_var//-/_}"
+    local on_path=false
+    local env_set=false
+
+    if command -v "$tool" &> /dev/null; then
+        on_path=true
+    fi
+
+    if [[ -v "$env_var" ]]; then
+        env_set=true
+    fi
+
+    if $on_path && $env_set; then
+        echo "Error: Both \$$env_var is set and '$tool' is on PATH. Please use only one." >&2
+        exit 1
+    elif $on_path; then
+        echo "$tool"
+    elif $env_set; then
+        echo "${!env_var}"
+    else
+        echo "Error: $tool not found. Either set \$$env_var environment variable or add '$tool' to PATH." >&2
+        exit 1
+    fi
+}