#include "gas167.h"
#if EEPROM_M95M02
#include "package.h"

extern int modbus[];
extern int Desk;
extern void ump_log_rs(void);

static const uint16_t gas167_info[GAS167_INFO_WORDS] = {
    0x4741U, 0x5331U, GAS167_PROFILE_VERSION, 167U,
    GAS167_REG_BASE, GAS167_REG_COUNT, GAS167_CAPABILITIES, 1U
};

int gas167_contains(uint16_t address)
{
    return (uint16_t)(address - GAS167_REG_BASE) < GAS167_REG_COUNT ||
        (uint16_t)(address - GAS167_INFO_BASE) < GAS167_INFO_WORDS;
}

static unsigned gas167_write(uint16_t offset, uint16_t value)
{
    /* Match the existing native Modbus write policy. These status words
     * cannot be overwritten and an invalid timeout cannot bypass protection. */
    if (Desk == dsk_LOAD && (offset == 0x7CU || offset == 0x7DU)) return 2;
    if (Desk == dsk_LOAD && offset == 0x52U &&
        (value == 0U || value > 60000U)) return 3;
    /* C28x int is one register word; reads always expose the raw uint16_t. */
    modbus[offset] = (int)value;
    if (offset == 127U) ump_log_rs();
    return 0;
}

unsigned gas167_prepare(unsigned function, uint16_t address, uint16_t value,
    int can, uint16_t *reply, unsigned *error)
{
    uint16_t offset;
    unsigned i, available;
    int info;
    if (!reply || !error) return 0;
    *error = 0;
    info = (uint16_t)(address - GAS167_INFO_BASE) < GAS167_INFO_WORDS;
    offset = (uint16_t)(address - (info ? GAS167_INFO_BASE : GAS167_REG_BASE));
    available = info ? GAS167_INFO_WORDS : GAS167_REG_COUNT;
    if (function != 3U && function != 6U) *error = 1;
    else if (offset >= available) *error = 2;
    else if (function == 6U) {
        *error = info ? 2U : gas167_write(offset, value);
    } else if (!value || value > GAS167_MAX_WORDS || (can && (value & 1U))) {
        *error = 3;
    } else if (value > available - offset) {
        *error = 2;
    } else {
        /* Validate the entire block before reading. A block cannot cross a
         * region boundary, wrap at 0xFFFF, or leak the hidden parameter word. */
        for (i = 0; i < value; ++i)
            reply[i] = info ? gas167_info[offset+i] : (uint16_t)modbus[offset+i];
        return value;
    }
    reply[0] = address;
    reply[1] = value;
    return 2;
}
#endif