# Builds the external post-quantum primitives Circe depends on:
#   - mlkem-native  -> ML-KEM-768
#   - mldsa-native  -> ML-DSA-44
#
# Both are compiled as single-compilation-unit (monolithic) builds: one C unit
# plus one assembly unit per library. The parameter set, namespace and native
# backend selection live in the config headers under contrib/config/, which are
# pulled in via -DML{K,D}_CONFIG_FILE.
#
# Each consumer of these libraries must still provide a randombytes()
# implementation:  int randombytes(uint8_t *out, size_t outlen);

cc = meson.get_compiler('c')

# ---------------------------------------------------------------------------
# Native-backend architecture flags
#
# The config headers enable the native backends whenever the compiler targets
# AArch64 or x86-64. Here we hand the compiler the ISA flags those backends
# need; on any other architecture we add nothing and the portable C backends
# are used instead.
# ---------------------------------------------------------------------------
native_arch_args = []
cpu = host_machine.cpu_family()

if cpu == 'x86_64'
    # AVX2 arithmetic backend + BMI2 for the Keccak/rejection-sampling paths.
    foreach arg : ['-mavx2', '-mbmi2']
        if cc.has_argument(arg)
            native_arch_args += arg
        endif
    endforeach
elif cpu == 'aarch64'
    # NEON arithmetic backend + the Armv8.4 SHA3 extension for native Keccak.
    if cc.has_argument('-march=armv8.4-a+sha3')
        native_arch_args += '-march=armv8.4-a+sha3'
    endif
endif

contrib_config_inc = include_directories('config')

# Freestanding, matching the rest of Circe: no libc is linked, and the config
# headers route the libraries' memcpy/memset/zeroize through common's
# circe_memcpy/circe_memset (hence the common_dep below).
pqc_c_args = [
    '-O3',
    '-ffreestanding',
    '-fno-stack-protector', # no libc: don't emit __stack_chk_fail references
    '-fomit-frame-pointer',
] + native_arch_args

# ---------------------------------------------------------------------------
# mlkem-native -> ML-KEM-768
# ---------------------------------------------------------------------------
mlkem_inc = include_directories('mlkem-native/mlkem')
mlkem_config_arg = '-DMLK_CONFIG_FILE="circe_mlkem_config.h"'

mlkem_lib = static_library(
    'circe-mlkem',
    [
        'mlkem-native/mlkem/mlkem_native.c',
        'mlkem-native/mlkem/mlkem_native_asm.S',
    ],
    c_args: pqc_c_args + [mlkem_config_arg],
    include_directories: [mlkem_inc, contrib_config_inc],
    dependencies: [common_dep],
)

mlkem_dep = declare_dependency(
    link_with: mlkem_lib,
    include_directories: [mlkem_inc, contrib_config_inc],
    compile_args: [mlkem_config_arg],
    dependencies: [common_dep],
)
set_variable(meson.project_name() + '_mlkem_dep', mlkem_dep)

# ---------------------------------------------------------------------------
# mldsa-native -> ML-DSA-44
# ---------------------------------------------------------------------------
mldsa_inc = include_directories('mldsa-native/mldsa')
mldsa_config_arg = '-DMLD_CONFIG_FILE="circe_mldsa_config.h"'

mldsa_lib = static_library(
    'circe-mldsa',
    [
        'mldsa-native/mldsa/mldsa_native.c',
        'mldsa-native/mldsa/mldsa_native_asm.S',
    ],
    c_args: pqc_c_args + [mldsa_config_arg],
    include_directories: [mldsa_inc, contrib_config_inc],
    dependencies: [common_dep],
)

mldsa_dep = declare_dependency(
    link_with: mldsa_lib,
    include_directories: [mldsa_inc, contrib_config_inc],
    compile_args: [mldsa_config_arg],
    dependencies: [common_dep],
)
set_variable(meson.project_name() + '_mldsa_dep', mldsa_dep)