MCP2210_PIN_IS_ALT0
if (b[MCP2210_GPIO_SRAM_GP0 + pin] != MCP2210_PIN_IS_ALT0) {
b[MCP2210_GPIO_SRAM_GP0 + pin] = MCP2210_PIN_IS_ALT0;
case MCP2210_PIN_IS_ALT0:
*gp = MCP2210_PIN_IS_ALT0;