embedded:io/spi fails to link on ESP8266 with non-RGB565LE display formats

[HipsterBrown]

Build environment: macOS
Moddable SDK version: 7.0.0
Target device: Moddable Three

Description
Including $(MODDABLE)/modules/io/manifest.json in a project targeting any ESP8266 board whose display format is not RGB565LE (e.g. Moddable Three, which uses Gray256) produces a linker error for the undefined symbol modSPITxSwap16.

Steps to Reproduce

1. Create a project whose manifest.json includes $(MODDABLE)/modules/io/manifest.json
2. Build for esp8266/moddable_three: mcconfig -d -m -p esp8266/moddable_three
3. See linker error:

  modules/io/spi/esp/spi.c: undefined reference to `modSPITxSwap16'
  collect2: error: ld returned 1 exit status

Expected behavior
The project links and flashes successfully.

Images
N/A

Other information
modules/io/spi/esp/spi.c calls modSPITxSwap16 unconditionally when spi->transform is set. However, in modules/pins/spi/esp/modSPI.c the function is only compiled when kCommodettoBitmapFormat == kCommodettoBitmapRGB565LE. On Moddable Three the format is Gray256, so the symbol is never emitted and the link fails.

Suggested fix — guard the call in spi.c with the same #if already used in modSPI.c, falling through to the plain modSPITx on non-RGB565LE targets:

// modules/io/spi/esp/spi.c  xs_spi_write
#if kCommodettoBitmapFormat == kCommodettoBitmapRGB565LE
      if (spi->transform)
              modSPITxSwap16(&spi->config, (uint8_t *)data, (uint16_t)count);
      else
#endif
              modSPITx(&spi->config, (uint8_t *)data, (uint16_t)count);

[phoddie]

Closing – see #1592. If the issue remains, please reopen.