SDK • Fastest OLED write?

Code:

;; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.;; SPDX-License-Identifier: BSD-3-Clause;.program st7789_lcd.side_set 1; This is just a simple clocked serial TX. At 125 MHz system clock we can; sustain up to 62.5 Mbps.; Data on OUT pin 0; Clock on side-set pin 0.wrap_target    out pins, 1   side 0 ; stall here if no data (clock low)    nop           side 1.wrap% c-sdk {// For optimal use of DMA bandwidth we would use an autopull threshold of 32,// but we are using a threshold of 8 here (consume 1 byte from each FIFO entry// and discard the remainder) to make things easier for software on the other sidestatic inline void st7789_lcd_program_init(PIO pio, uint sm, uint offset, bool cpol, uint data_pin, uint clk_pin, float clk_div) {    pio_gpio_init(pio, data_pin);    pio_gpio_init(pio, clk_pin);    pio_sm_set_consecutive_pindirs(pio, sm, data_pin, 1, true);    pio_sm_set_consecutive_pindirs(pio, sm, clk_pin, 1, true);    pio_sm_config c = st7789_lcd_program_get_default_config(offset);    sm_config_set_sideset_pins(&c, clk_pin);    sm_config_set_out_pins(&c, data_pin, 1);    sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);    sm_config_set_clkdiv(&c, clk_div);    sm_config_set_out_shift(&c, false, true, 8);// The pin muxes can be configured to invert the output (among other things    // and this is a cheesy way to get CPOL=1    gpio_set_outover(clk_pin, cpol ? GPIO_OVERRIDE_INVERT : GPIO_OVERRIDE_NORMAL);    pio_sm_init(pio, sm, offset, &c);    pio_sm_set_enabled(pio, sm, true);}// Making use of the narrow store replication behaviour on RP2040 to get the// data left-justified (as we are using shift-to-left to get MSB-first serial)static inline void st7789_lcd_put(PIO pio, uint sm, uint8_t x) {    while (pio_sm_is_tx_fifo_full(pio, sm))        ;    *(volatile uint8_t*)&pio->txf[sm] = x;}// SM is done when it stalls on an empty FIFOstatic inline void st7789_lcd_wait_idle(PIO pio, uint sm) {    uint32_t sm_stall_mask = 1u << (sm + PIO_FDEBUG_TXSTALL_LSB);    pio->fdebug = sm_stall_mask;    while (!(pio->fdebug & sm_stall_mask))        ;}%}