semihosting: fix return value of SYS_READ and SYS_WRITE

ARM/RISC-V semihosting calls SYS_READ/SYS_WRITE require
inversion of the result value as described in
"Semihosting for AArch32 and AArch64". Prior to
this patch, this was done correctly only if
(semihosting->is_fileio==false).

This patch has been tested with STM32F446.

Change-Id: I1b34c8d8393f7dfa66ee6539904a2eaf8f9154b0
Signed-off-by: Pavel Kirienko <pavel.kirienko@gmail.com>
Fixes: https://sourceforge.net/p/openocd/tickets/232/
Reviewed-on: https://review.openocd.org/c/openocd/+/6803
Tested-by: jenkins
Reviewed-by: Tim Newsome <tim@sifive.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

diff --git a/src/target/semihosting_common.c b/src/target/semihosting_common.c
index 2c7f4a118c27ba20ba9272163d9baa679957287e..cae6afba2fb242c4e879411ee42e6091d76f16c5 100644 (file)
--- a/src/target/semihosting_common.c
+++ b/src/target/semihosting_common.c
@@ -1641,17 +1641,11 @@ static int semihosting_common_fileio_end(struct target *target, int result,
         */
        switch (semihosting->op) {
                case SEMIHOSTING_SYS_WRITE:     /* 0x05 */
+               case SEMIHOSTING_SYS_READ:      /* 0x06 */
                        if (result < 0)
-                               semihosting->result = fileio_info->param_3;
+                               semihosting->result = fileio_info->param_3;  /* Zero bytes read/written. */
                        else
-                               semihosting->result = 0;
-                       break;
-
-               case SEMIHOSTING_SYS_READ:      /* 0x06 */
-                       if (result == (int)fileio_info->param_3)
-                               semihosting->result = 0;
-                       if (result <= 0)
-                               semihosting->result = fileio_info->param_3;
+                               semihosting->result = (int64_t)fileio_info->param_3 - result;
                        break;
 
                case SEMIHOSTING_SYS_SEEK:      /* 0x0a */