Perhaps you could use a CSS based solution to your indent requirement which does involve replacing your spaces with a <br/> and using some CSS that I normally use to fake a list.
Code:
p.function {
margin-top: 1.5em;
font-family: listing;
font-size: 0.9em;
font-weight: normal;
font-style: italic;
text-align: left;
color: darkblue;
background-color: #CCFFFF;
border-top: #00CCCC solid 2px;
text-indent: -2.5em;
margin-left: 2.5em;
margin-right: 1.25em;
}
Code:
<p class="function">esp_err_t <span class="function_name">i2c_new_master_bus</span>(
<br/>const i2c_master_bus_config_t *bus_config,
<br/>i2c_master_bus_handle_t *ret_bus_handle)</p>
Please note that this will wrap to a single line when prettified and you will need to play with the alignment of the top border since the 2.5em margin will affect it.