From 10dd330e3c6b0eca2df0a053f178a95e105f4da8 Mon Sep 17 00:00:00 2001
From: d00f <8052722+DrDoof@users.noreply.github.com>
Date: Fri, 18 Sep 2026 02:39:52 +0200
Subject: [PATCH] httpd: subtract through a pointer of known type

uip_appdata is void *, so p - uip_appdata subtracts pointers of
different types. SDCC accepts it, C does not, and no host compiler will
build the file for a unit test. Cast to the type the byte count is meant
in; the generated firmware code is unchanged.
---
 httpd/httpd.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/httpd/httpd.c b/httpd/httpd.c
index 74c11148..aba33e40 100644
--- a/httpd/httpd.c
+++ b/httpd/httpd.c
@@ -559,7 +559,7 @@ static void handle_config_fragment(__xdata uint8_t *p)
 	__xdata uint16_t frag_len;
 	uint8_t taken;
 
-	frag_len = uip_len - (p - uip_appdata);
+	frag_len = uip_len - (p - (__xdata uint8_t *)uip_appdata);
 	if (pre_acc + frag_len >= CONFIG_UPLOAD_BUF) {
 		print_string("Configuration too large, aborting.\n");
 		config_upload = 0;
@@ -589,7 +589,7 @@ static void handle_firmware_fragment(__xdata uint8_t *p)
 	__xdata struct httpd_state * __xdata s = &(uip_conn->appstate);
 	__xdata uint16_t frag_len, payload_start;
 
-	frag_len = uip_len - (p - uip_appdata);
+	frag_len = uip_len - (p - (__xdata uint8_t *)uip_appdata);
 	if (pre_acc + frag_len >= CONFIG_UPLOAD_BUF) {
 		print_string("Firmware upload header too large, aborting.\n");
 		config_upload = 0;
@@ -684,7 +684,7 @@ static uint8_t post_body_take(__xdata uint8_t *p)
 		send_bad_request();
 		return 0;
 	}
-	have = uip_len - (p - uip_appdata);
+	have = uip_len - (p - (__xdata uint8_t *)uip_appdata);
 	if (have >= content_length) {
 		p[content_length] = NUL;
 		return 1;