[baremetal] Avoid narrow loop counters etc
Use `uint_fast8_t` instead of `unsigned char` in various loop-type
situations. This avoids the need for a 16 or 32-bit system to insert
explicit narrow-to-8-bit instructions.
Not the result of an exhaustive source analysis, rather inspecting
the disassembly output for a cut-down Cortex-M0+ build looking for
UXTB etc instructions, so there could well be more in the complete
configuration.
Signed-off-by: Kevin Bracey <kevin.bracey@arm.com>
diff --git a/library/aes.c b/library/aes.c
index 04c8208..f7a4898 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -547,7 +547,7 @@
* |0x10|0x03|0x10|0x10|0x10|0x04|0x00| ... |0x04|0x00|0x04|0x03|0x07|
*/
#if defined(MBEDTLS_AES_SCA_COUNTERMEASURES)
-static int aes_sca_cm_data_randomize( uint8_t *tbl, uint8_t tbl_len )
+static int aes_sca_cm_data_randomize( uint8_t *tbl, int tbl_len )
{
int i = 0, j, is_even_pos, dummy_rounds, num;
diff --git a/library/ccm.c b/library/ccm.c
index 750ec9e..e54a995 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -40,6 +40,7 @@
#include "mbedtls/platform.h"
#include "mbedtls/platform_util.h"
+#include <stdint.h>
#include <string.h>
#if defined(MBEDTLS_SELF_TEST) && defined(MBEDTLS_AES_C)
@@ -157,8 +158,8 @@
unsigned char *tag, size_t tag_len )
{
int ret = MBEDTLS_ERR_PLATFORM_FAULT_DETECTED;
- unsigned char i;
- unsigned char q;
+ uint_fast8_t i;
+ uint_fast8_t q;
size_t len_left, olen;
unsigned char b[16];
unsigned char y[16];
@@ -183,7 +184,7 @@
if( add_len > 0xFF00 )
return( MBEDTLS_ERR_CCM_BAD_INPUT );
- q = 16 - 1 - (unsigned char) iv_len;
+ q = (uint_fast8_t) (16 - 1 - iv_len);
/*
* First block B_0:
@@ -368,7 +369,7 @@
{
int ret = MBEDTLS_ERR_PLATFORM_FAULT_DETECTED;
unsigned char check_tag[16];
- unsigned char i;
+ uint_fast8_t i;
int diff;
CCM_VALIDATE_RET( ctx != NULL );
diff --git a/library/cipher.c b/library/cipher.c
index e0fd39d..6eab899 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -36,6 +36,7 @@
#include "mbedtls/platform_util.h"
#include <stdlib.h>
+#include <stdint.h>
#include <string.h>
#if defined(MBEDTLS_CHACHAPOLY_C)
@@ -591,7 +592,7 @@
size_t data_len )
{
size_t padding_len = output_len - data_len;
- unsigned char i;
+ uint_fast8_t i;
for( i = 0; i < padding_len; i++ )
output[data_len + i] = (unsigned char) padding_len;
@@ -601,7 +602,7 @@
size_t *data_len )
{
size_t i, pad_idx;
- unsigned char padding_len, bad = 0;
+ uint_fast8_t padding_len, bad = 0;
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
@@ -631,7 +632,7 @@
size_t output_len, size_t data_len )
{
size_t padding_len = output_len - data_len;
- unsigned char i = 0;
+ uint_fast8_t i = 0;
output[data_len] = 0x80;
for( i = 1; i < padding_len; i++ )
@@ -642,7 +643,7 @@
size_t *data_len )
{
size_t i;
- unsigned char done = 0, prev_done, bad;
+ uint_fast8_t done = 0, prev_done, bad;
if( NULL == input || NULL == data_len )
return( MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA );
@@ -670,7 +671,7 @@
size_t output_len, size_t data_len )
{
size_t padding_len = output_len - data_len;
- unsigned char i = 0;
+ uint_fast8_t i = 0;
for( i = 1; i < padding_len; i++ )
output[data_len + i - 1] = 0x00;
diff --git a/library/ecp.c b/library/ecp.c
index 3cdd566..ff13e88 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -82,6 +82,7 @@
#include "mbedtls/threading.h"
#include "mbedtls/platform_util.h"
+#include <stdint.h>
#include <string.h>
#if !defined(MBEDTLS_ECP_ALT)
@@ -183,7 +184,7 @@
*/
static void ecp_restart_rsm_free( mbedtls_ecp_restart_mul_ctx *ctx )
{
- unsigned char i;
+ uint_fast8_t i;
if( ctx == NULL )
return;
@@ -1753,7 +1754,7 @@
unsigned char i )
{
int ret;
- unsigned char ii, j;
+ uint_fast8_t ii, j;
/* Ignore the "sign" bit and scale down */
ii = ( i & 0x7Fu ) >> 1;
@@ -2019,7 +2020,8 @@
mbedtls_ecp_restart_ctx *rs_ctx )
{
int ret;
- unsigned char w, p_eq_g, i;
+ unsigned char w, p_eq_g;
+ uint_fast8_t i;
size_t d;
unsigned char T_size, T_ok;
mbedtls_ecp_point *T;
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 24dbb7d..5f88fef 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -35,6 +35,8 @@
#if defined(MBEDTLS_SSL_TLS_C)
+#include <stdint.h>
+
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
@@ -2932,7 +2934,7 @@
else if( transform->ivlen == 12 && transform->fixed_ivlen == 12 )
{
/* ChachaPoly: fixed XOR sequence number */
- unsigned char i;
+ uint_fast8_t i;
mbedtls_platform_memcpy( iv, transform->iv_enc, transform->fixed_ivlen );
@@ -3317,7 +3319,7 @@
if( transform->ivlen == 12 && transform->fixed_ivlen == 12 )
{
/* ChachaPoly: fixed XOR sequence number */
- unsigned char i;
+ uint_fast8_t i;
mbedtls_platform_memcpy( iv, transform->iv_dec, transform->fixed_ivlen );
@@ -4021,7 +4023,7 @@
uint32_t ratio =
mbedtls_ssl_conf_get_hs_timeout_max( ssl->conf ) /
mbedtls_ssl_conf_get_hs_timeout_min( ssl->conf ) + 1;
- unsigned char doublings = 1;
+ int_fast8_t doublings = 1;
while( ratio != 0 )
{
@@ -8604,7 +8606,7 @@
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( MBEDTLS_SSL_TRANSPORT_IS_DTLS( ssl->conf->transport ) )
{
- unsigned char i;
+ uint_fast8_t i;
/* Remember current epoch settings for resending */
ssl->handshake->alt_transform_out = ssl->transform_out;
diff --git a/tinycrypt/ecc.c b/tinycrypt/ecc.c
index ba4a3ac..a6c8467 100644
--- a/tinycrypt/ecc.c
+++ b/tinycrypt/ecc.c
@@ -160,7 +160,7 @@
0x76, 0x0a, 0xe2, 0xbc, 0xce, 0x2a, 0xa2, 0xc6,
0x38, 0xf2, 0x19, 0x1d, 0x76, 0x72, 0x93, 0x49,
};
- unsigned char diff = 0;
+ int diff = 0;
unsigned char tmp1, tmp2;
volatile unsigned i;
@@ -177,7 +177,7 @@
/* i should be 32 */
mbedtls_platform_random_delay();
- diff |= (unsigned char) i ^ 32;
+ diff |= i ^ 32;
return diff;
}