From 3d93c9348cd4b4233857f224b52a3fd1b01bf0eb Mon Sep 17 00:00:00 2001 From: Stephan Hadinger Date: Mon, 6 Nov 2023 20:53:59 +0100 Subject: [PATCH] Allow bytes get() to retrieve 3-bytes values --- src/be_byteslib.c | 46 ++++++++++++++++++++++++++++++++++++++++++++-- tests/bytes.be | 5 +++++ 2 files changed, 49 insertions(+), 2 deletions(-) diff --git a/src/be_byteslib.c b/src/be_byteslib.c index 665d630..c26a45d 100644 --- a/src/be_byteslib.c +++ b/src/be_byteslib.c @@ -356,6 +356,40 @@ static uint16_t buf_get2_be(buf_impl* attr, size_t offset) return 0; } +static uint32_t buf_get3_le(buf_impl* attr, size_t offset) +{ + if ((int32_t)offset + 2 < attr->len) { + return attr->bufptr[offset] | (attr->bufptr[offset+1] << 8) | (attr->bufptr[offset+2] << 16); + } + return 0; +} + +static uint32_t buf_get3_be(buf_impl* attr, size_t offset) +{ + if ((int32_t)offset + 2 < attr->len) { + return attr->bufptr[offset+2] | (attr->bufptr[offset+1] << 8) | (attr->bufptr[offset] << 16); + } + return 0; +} + +static void buf_set3_le(buf_impl* attr, size_t offset, uint32_t data) +{ + if ((int32_t)offset + 2 < attr->len) { + attr->bufptr[offset] = data & 0xFF; + attr->bufptr[offset+1] = (data >> 8) & 0xFF; + attr->bufptr[offset+2] = (data >> 16) & 0xFF; + } +} + +static void buf_set3_be(buf_impl* attr, size_t offset, uint32_t data) +{ + if ((int32_t)offset + 2 < attr->len) { + attr->bufptr[offset+2] = data & 0xFF; + attr->bufptr[offset+1] = (data >> 8) & 0xFF; + attr->bufptr[offset] = (data >> 16) & 0xFF; + } +} + static void buf_set4_le(buf_impl* attr, size_t offset, uint32_t data) { if ((int32_t)offset + 3 < attr->len) { @@ -832,12 +866,18 @@ static int m_get(bvm *vm, bbool sign) case 2: ret = buf_get2_le(&attr, idx); if (sign) { ret = (int16_t)(uint16_t) ret; } break; + case 3: ret = buf_get3_le(&attr, idx); + if (sign & (ret & 0x800000)) { ret = ret | 0xFF000000; } + break; case 4: ret = buf_get4_le(&attr, idx); break; case -2: ret = buf_get2_be(&attr, idx); if (sign) { ret = (int16_t)(uint16_t) ret; } break; + case -3: ret = buf_get3_be(&attr, idx); + if (sign & (ret & 0x800000)) { ret = ret | 0xFF000000; } + break; case -4: ret = buf_get4_be(&attr, idx); break; - default: be_raise(vm, "type_error", "size must be -4, -2, -1, 0, 1, 2 or 4."); + default: be_raise(vm, "type_error", "size must be -4, -3, -2, -1, 0, 1, 2, 3 or 4."); } be_pop(vm, argc - 1); if (vsize != 0) { @@ -911,10 +951,12 @@ static int m_set(bvm *vm) case -1: /* fallback below */ case 1: buf_set1(&attr, idx, value); break; case 2: buf_set2_le(&attr, idx, value); break; + case 3: buf_set3_le(&attr, idx, value); break; case 4: buf_set4_le(&attr, idx, value); break; case -2: buf_set2_be(&attr, idx, value); break; + case -3: buf_set3_be(&attr, idx, value); break; case -4: buf_set4_be(&attr, idx, value); break; - default: be_raise(vm, "type_error", "size must be -4, -2, -1, 0, 1, 2 or 4."); + default: be_raise(vm, "type_error", "size must be -4, -3, -2, -1, 0, 1, 2, 3 or 4."); } be_pop(vm, argc - 1); m_write_attributes(vm, 1, &attr); /* update attributes */ diff --git a/tests/bytes.be b/tests/bytes.be index 6a481d6..966006b 100644 --- a/tests/bytes.be +++ b/tests/bytes.be @@ -257,3 +257,8 @@ assert(!bytes()) assert(bool(bytes("00")) == true) assert(bytes("01").tobool() == true) assert(bytes("02")) + +# retrieving 3-bytes little/big endian +a = bytes("01020304") +assert(a.get(1, 3) == 0x040302) +assert(a.get(1, -3) == 0x020304)