sbc produce carry flag

Code:

void sbc_zeropage (struct NESEmu *emu){        struct CPUNes *cpu = &emu->cpu;        uint16_t addr = zeropage (emu);        uint8_t val = addr < RAM_MAX? emu->ram[addr]: emu->mem[addr - 0x8000];        repetitive_acts (emu,                         STATUS_FLAG_NF|STATUS_FLAG_ZF|STATUS_FLAG_CF|STATUS_FLAG_VF,                        &cpu->A,                         cpu->A - val - ((emu->cpu.P & STATUS_FLAG_CF)? 0: 1),                        eq,                        (3 << 8) | 2);}static void repetitive_acts (struct NESEmu *emu,                 uint8_t flags,                uint8_t *reg,                uint8_t result,                void (*eq) (uint8_t *r0, uint8_t r1),                uint16_t cycles_and_bytes){        struct CPUNes *cpu = &emu->cpu;        uint8_t carry = 0;        if (cpu->P & STATUS_FLAG_CF) carry = 1;        cpu->P &= ~(flags);        check_flags (cpu, flags, *reg, result);        eq (reg, result);        wait_cycles (emu, cycles_and_bytes >> 8);        emu->cpu.PC += (cycles_and_bytes & 0xff);}static void eq (uint8_t *r0, uint8_t r1){        *r0 = r1; }static void check_flags (struct CPUNes *cpu, uint8_t flags, uint8_t reg, uint8_t ret){        if (flags & STATUS_FLAG_NF) {                if (ret & 0x80) {                        cpu->P |= STATUS_FLAG_NF;                }        }        if (flags & STATUS_FLAG_ZF) {                if (ret == 0) {                        cpu->P |= STATUS_FLAG_ZF;                }        }        if (flags & STATUS_FLAG_CF) {                if (ret < reg) {                        cpu->P |= STATUS_FLAG_CF;                }        }        if ((ret & 0x80) && (!(reg & 0x80)))                cpu->P |= STATUS_FLAG_VF;        else if ((!(ret & 0x80)) && (reg & 0x80))                cpu->P |= STATUS_FLAG_VF;}